Taken from https://codeforces.com/blog/entry/55274

• https://www.spoj.com/problems/ADAJOBS/

• URI 2226 (5) //[NICE][NUMBERS][DP]

• https://www.spoj.com/problems/SUB_PROB/en/

• https://codeforces.com/contest/696/problem/D 8

• https://www.spoj.com/problems/AHOCUR/ 5 //Aho-Corassic + DP

• https://www.codechef.com/problems/LYRC (5) //Sample aho-brute-force

• https://codeforces.com/problemset/problem/346/B //Proposed by bradyawn

• 6861 [LA] //CYK

• UVA 10679 //Suffix Automat

• https://www.spoj.com/problems/STRMATCH/ //Suffix Automat — trie might do too

• https://www.spoj.com/problems/NSUBSTR2/ //Suffix Automaton

• UVA 12519

• https://www.spoj.com/problems/ARBITRAG/ (4) //Or Floyd-Warshall

• https://www.spoj.com/problems/ADACYCLE/ [FW]

• 6151 — Beehives (4) //[NICE] //Search for shortest cycle

• https://devskill.com/CodingProblems/ViewProblem/60

• https://devskill.com/CodingProblems/ViewProblem/150

• 11312 UVA (3)

• 11392 UVA (4)

• https://codeforces.com/contest/653/problem/E (6)

• https://codeforces.com/contest/769/problem/C 5 //FL:ODD/**** | bfs+greed NICE

• 10968 UVA (3) //EASY + NICE (bfs withot <=2 nodes)

• https://codeforces.com/contest/796/problem/D (3) //NICE+EASY ... print visited in bfs (not par)

• 10888 UVA (4) //VERY NICE — but not main technique ... ++ DP /or/ MCMF

• https://codeforces.com/contest/821/problem/D (5) //VERY NICE — Consider only points not GRID

• https://www.spoj.com/problems/DIGOKEYS/ (4) //Easy [Nice problem — weird statement]

• https://www.spoj.com/problems/SPIKES/ (3) //Easy bfs (# of 's' * 2)

• https://www.spoj.com/problems/MULTII/ (4) //VERY NICE: BFS over numbers (K*10+d)%N

• https://www.spoj.com/problems/ADV04F1/ (5) //VERY NICE: [imple] ~ N^4*BigConstant

• https://www.spoj.com/problems/INVESORT/ (5) //Big limit (really usefull :P)

• https://codeforces.com/contest/59/problem/E (5) //[NICE][DOUBLE-STATES][SET]

• https://codeforces.com/contest/877/problem/D (4) //[NICE] Add vector to # of states

• 10977 UVA (3)

• 928 UVA (3)

• 13116 UVA (4)

• 314 UVA (3)

• 11487 UVA (4)

• 5622 LA (7)

• 11931 UVA (5)

• https://www.spoj.com/problems/KNMOVE/ 3 //simple knights

• https://www.spoj.com/problems/SERGRID/ 3 //almost classical

• https://www.spoj.com/problems/NAKANJ/ 3 //Classical chess — KNIGHT

• https://www.spoj.com/problems/PUCMM223/ (4) //NICE (but not many languages) — 2 moving [x][y]

• https://www.spoj.com/problems/SPIRALGR/ (4) //NICE (not typical) [SIEVE]

• https://www.spoj.com/problems/DCEPC706/ (4) //NICE — travelling outside

• https://codeforces.com/contest/35/problem/C (3) //No obstacles [multiple starts]

• https://devskill.com/CodingProblems/ViewProblem/394 (2) //Multiplication (or math)

• https://codeforces.com/contest/66/problem/A (2) //Big + iffs + implementation

• UVA — 10183

• 10106 — Product [UVA]

• 10523 — Very Easy !!! [UVA]

• 787 — Maximum Sub-sequence Product [UVA]

• 2871 — Rhyme Schemes [LA][BELL]

• UVA — 10497

• https://www.spoj.com/problems/MUL/en/

• https://www.spoj.com/problems/ITRIX_E/

• 11115 — Uncle Jack

• 11448 — Who said crisis? [UVA]

• https://www.spoj.com/problems/GCD2/

• 10083 — Division [UVA]

• 11830 — Contract Revision [UVA]

• 1230 — MODEX [UVA]

• https://www.spoj.com/problems/NUMPLAY/

• 10519 — UVA

• 7651 — Pascal's Hyper-Pyramids [LA]

• 11344 — The Huge One [UVA]

• 10303 — How Many Trees? [UVA]

• https://www.spoj.com/problems/FAST2/

• 495 — Fibonacci Freeze [UVA]

• 10023 — Square root [UVA]

• https://www.spoj.com/problems/SKYLINE/

• https://www.spoj.com/problems/NITT2/

• 11879 — Multiple of 17

• https://www.spoj.com/problems/MINNUM/

• 10494 — If We Were a Child Again [UVA]

• 10013 — Super long sums [UVA]

• 10925 — Krakovia [UVA]

• 10814 — Simplifying Fractions [UVA]

• 619 — Numerically Speaking [UVA]

• 713 — Adding Reversed Numbers [UVA]

• 1226 — Numerical surprises [UVA]

• 623 — 500! [UVA]

• https://codeforces.com/problemset/problem/18/D

• https://www.spoj.com/problems/NUMTSN/

• https://www.codechef.com/problems/FRJUMP

• 10220 — I Love Big Numbers ! [UVA]

• https://www.hackerrank.com/contests/projecteuler/challenges/euler025

• https://www.hackerrank.com/contests/projecteuler/challenges/euler020

• 11645 UVA 4

• Gym — 100866A [ACM ICPC 2005–2006 NEERC Moscow Subregional Contest]

• CSQUARE [SPOJ]

• https://www.spoj.com/problems/PARCARD1/

• 10070 — Leap Year or Not Leap Year and .. [UVA]

• https://www.spoj.com/problems/SOLDIERS/

• 12333 — Revenge of Fibonacci [UVA]

• https://www.spoj.com/problems/NDIVPHI/

• https://www.spoj.com/problems/IWGBS/ [UVA]

• https://www.spoj.com/problems/POP3/ [Prime-Test]

• https://www.spoj.com/problems/VGCD/

• https://www.spoj.com/problems/NDIVPHI2/

• 12924 — Immortal Rabbits [UVA]

• Count the Trees [UVA][10007]

• 10198 — Counting [UVA]

• 11375 UVA 3

• https://www.spoj.com/problems/MINNUM/ 3 // BIG/9+!!(BIG%9)

• 10844 UVA 4 //Bell numbers + big (might be slightly slow!)

• https://www.spoj.com/problems/NITT2/ 2 //Divisibility by two constants

• https://www.spoj.com/problems/NUMPLAY/ (3) //With DP

• https://www.spoj.com/problems/IWGBS/ (3) //Fibonacci 10^4

• https://www.spoj.com/problems/PUCMM025/ (2) //Divisibility by 1 → 9

• https://www.spoj.com/problems/CSQUARE/ (3) //Converse + Power

• https://codeforces.com/contest/17/problem/D (5) //B^(N-1)*(B-1)%C [B/N are big]

• https://codeforces.com/contest/920/problem/G (5) //[NICE][MATH][IE]

• https://codeforces.com/contest/140/problem/C (4) //[NICE][GREEDY]

• https://codeforces.com/contest/898/problem/E (4) //[NICE][SIMPLE][PREPROCESS]

• https://codeforces.com/contest/888/problem/C (3) //Can be done without BS

• https://codeforces.com/contest/68/problem/B (3) //[EASY][DOUBLE]

• https://codeforces.com/contest/42/problem/A (2) //Or simple math

• https://codeforces.com/contest/883/problem/I (4) //[NICE][SET][2Pointers]

• https://codeforces.com/contest/51/problem/C (4) //[NICE][GREEDY-CHECK]

• https://codeforces.com/contest/729/problem/C 3

• https://codeforces.com/contest/714/problem/D 8

• 13150 (UVA) 4

• https://codeforces.com/contest/749/problem/D 5

• 11692 (UVA) 4

• 11516 (UVA) 3

• https://codeforces.com/contest/760/problem/B 3

• https://codeforces.com/contest/675/problem/D 4 //dunno — solvable with treap

• https://www.spoj.com/problems/NDS/ 4 //BS over LIS

• https://www.spoj.com/problems/VECTAR4/ 3

• https://codeforces.com/contest/767/problem/D 4 //NICE

• https://codeforces.com/contest/627/problem/D (7) //with dp — NICE

• https://codeforces.com/contest/779/problem/D (3) //NICE + EASY

• https://www.spoj.com/problems/CNTINDX/ (4) //Map+BS === OK

• 13177 UVA (3) //BS over answer == OK

• https://codeforces.com/contest/801/problem/C (3) //BS + SUM -EASY

• https://codeforces.com/contest/803/problem/D (3) //BS by answer

• https://codeforces.com/contest/807/problem/C (3) //Or math

• https://codeforces.com/contest/818/problem/F (4) //NICE — Live VS Clique

• https://codeforces.com/contest/845/problem/E (5) //VERY NICE — min(X,Y) .. add time, repeat

• https://www.spoj.com/problems/MATHLOVE/ (2) //BS + Gaus (or otter ways)

• https://www.spoj.com/problems/SABBIRGAME/ (3) //Binary search over answer ::max(0,ANS)

• https://codeforces.com/contest/846/problem/D (4) //BS+Precalculation OR 2D-RMQ

• https://www.spoj.com/problems/RPLC/ (3) //Classical

• https://www.spoj.com/problems/TRIGALGE/ (2) //On doubles — simple function given

• https://www.spoj.com/problems/ABA12E/ (4) //VERY NICE — BS on answer + 2Pointers

• https://codeforces.com/contest/847/problem/E (4) //NICE: Back+Front OR Front+Back

• https://www.spoj.com/problems/MAIN8_C/ (3) //Classical — simultion over array

• https://www.spoj.com/problems/FUNFACT/ (4) //VERY NICE — Sterling Approximation

• https://codeforces.com/contest/16/problem/C (3) //[or math][simple formula check]

• https://codeforces.com/contest/21/problem/C (3) //[NICE][prefix-sum+lower_bound]

• https://codeforces.com/contest/24/problem/E (5) //[doubles]

• https://codeforces.com/contest/875/problem/E (6) //VERY NICE [BS][Keep possible places]

• https://codeforces.com/contest/879/problem/C (3) //[NICE] one of each operation is enough

• https://codeforces.com/contest/92/problem/B (2) //Bit addition/shifting (but big number)

• https://codeforces.com/contest/907/problem/C (3) //Nice but ugly statement: sets

• 11659 UVA (4)

• 11535 UVA (4)

• https://codeforces.com/contest/779/problem/E (5) //NICE + Parsing

• https://www.spoj.com/problems/EC_CONB/ (1) //reverse numbers

• https://codeforces.com/contest/769/problem/D (4) //freq + brute-force

• https://www.spoj.com/problems/HAP01/ (2) //builtin_popcount

• https://codeforces.com/contest/862/problem/C (3) //VERY NICE — Random works well

• https://www.spoj.com/problems/KOMPICI/ (4) //NICE — Bitmask over digits

• https://www.spoj.com/problems/ADACOINS/

• https://www.spoj.com/problems/ADACHERY/

• https://www.spoj.com/problems/ADAFUROW/

• https://codeforces.com/contest/914/problem/F (7) //[VERY NICE][POLYMUL-LIKE][BRUTE]

• https://codeforces.com/contest/117/problem/C (5) //Finding 3cycles in directed graph [NICE]

• https://codeforces.com/contest/754/problem/E 6

• https://www.spoj.com/problems/UCBINTC/ 5 //polymul with bitset

• https://codeforces.com/contest/33/problem/D (4) //VERY NICE [LCA works too]

• https://codeforces.com/contest/918/problem/C (4) //Brute-force+Bitset (or...)

• https://codeforces.com/contest/118/problem/E (4) //[NICE]//Orientation [+DFS]

• 315 — Network

• 796 — Critical Links

• UVA 12363

• Gym 100114J [2012-2013 ACM-ICPC, NEERC, Central Subregional Contest]

• https://www.spoj.com/problems/ONBRIDGE/ [ONLINE][HARD][NICE][D&C]

• https://codeforces.com/contest/732/problem/F 7

• https://codeforces.com/contest/700/problem/C 7

• https://www.spoj.com/problems/EC_P/ (3) //bridges ONLY

• https://www.spoj.com/problems/SUBMERGE/ (3) //Direct articulation

• https://www.spoj.com/problems/GRAFFDEF/ (5) //Bridge tree

• https://codeforces.com/contest/1000/problem/E // Sugested by Muhanad_Alwarareh

• https://codeforces.com/gym/101806/problem/X (6) //[VERY NICE][DFS][IFS][OBSERVATION]

• 8259 — High Score LA //[VERY NICE][TS works too] add only low number to minimum (NOT WORKING?)

• https://codeforces.com/contest/922/problem/B (2) //Test all pairs — observe 3rd

• https://codeforces.com/contest/919/problem/B (1) //Simply simulate

• https://codeforces.com/contest/146/problem/B (2) //Test all bigger numbers

• https://codeforces.com/contest/911/problem/B (1)

• 7692 — Square Deal (4) //Permutations+Swap

• https://codeforces.com/contest/907/problem/A (2) //try all triples 0→ 200

• https://codeforces.com/contest/124/problem/B (3) //next-permutation

• https://codeforces.com/contest/910/problem/C (3) //Next-permutation

• https://codeforces.com/contest/898/problem/B (2) //Try all possibilities

• 6160 — Countdown (5) //[NICE][DFS][EFFICIENT?]

• https://codeforces.com/contest/122/problem/C (3) //Just around 2^10 lucky [RECURSION]

• 7899 — Mr. Panda and Strips (4) //Weak test-cases

• 7671 What a Beautiful Lake (2) //Try up/down from every node

• https://codeforces.com/contest/110/problem/A (1) //4 or 7

• https://codeforces.com/contest/106/problem/B (2) //Cycles -_-

• https://codeforces.com/contest/895/problem/A (2) //All segments [in circle]

• https://codeforces.com/contest/893/problem/B (2) //Try each divisor

• https://codeforces.com/contest/894/problem/A (1) //3-cycles

• https://codeforces.com/contest/892/problem/C (3) //Try to find "1" ASAP

• https://codeforces.com/contest/102/problem/A (2) //Iterate over all triples

• https://codeforces.com/contest/96/problem/B (2) //Check all

• https://codeforces.com/contest/94/problem/B (1) //3cycles

• https://codeforces.com/contest/887/problem/B (3) //Test all numbers

• https://codeforces.com/gym/101597/problem/A (4) //[MATH][MODULO][SIMULATION]

• https://codeforces.com/contest/68/problem/C (5) //[VERY NICE][RECURSION][MAX COST MIN FLOW]

• https://codeforces.com/contest/68/problem/A (1) //Simple simulation

• https://codeforces.com/contest/66/problem/B (2) //Test always whole platform

• https://codeforces.com/contest/879/problem/C (3) //[NICE] one of each operation is enough

• https://codeforces.com/contest/46/problem/C (2) //[2pointers][N^2 works too]

• https://codeforces.com/contest/47/problem/D (4) //[Implementation][DFS]

• https://codeforces.com/contest/51/problem/D (4) //Check all/check without 1s/2nd

• https://code-festival-2017-qualc.contest.atcoder.jp/tasks/code_festival_2017_qualc_b (2)

• https://codeforces.com/contest/53/problem/B (3) //at most 60 possibilities

• https://codeforces.com/contest/55/problem/B (3) //Try all permutations & possibilities [NICE]

• https://codeforces.com/contest/877/problem/B (3) //NICE [N^2][PrefixSum]

• LA 6623 — Battle for Silver (3) //4 for-cycles inside ~ K4 search

• UVA 12169 (2)

• https://codeforces.com/contest/725/problem/C 4

• https://codeforces.com/contest/725/problem/E 6

• https://codeforces.com/contest/724/problem/B 3

• 11961 UVA (2)

• 11898 UVA (4)

• 11659 UVA (4)

• https://codeforces.com/contest/753/problem/C 7

• 11699 UVA (4)

• 11548 UVA (3)

• 11471 UVA (5) //With dynamic programming

• https://codeforces.com/contest/698/problem/D 8 //with geometry

• https://codeforces.com/gym/101840 F //[NICE][BS][DISTANCE]

• 11206 UVA (6) //4^20 (but somehow passes)

• 11214 UVA (6) //Úvaha + pruning

• 11127 UVA (4) //Simple dfs [just realize you can do so]

• https://www.spoj.com/problems/BOKAM143SOU/ (3) //just implement for-cycles

• https://www.spoj.com/problems/BLOPER/ (4) dfs with little pruning

• 13173 UVA (3) //just brute-force + branching

• https://codeforces.com/contest/799/problem/D (4) //VERY NICE [only top 34 needed] — trick with 2 [~20]

• 10890 UVA (4) //Simple brute-force times out, but with simple pruning AC (answer detection

• https://codeforces.com/contest/813/problem/B (3) //All*All (BF) care for overflow! NICE & EASY

• https://codeforces.com/contest/817/problem/C (3) //Check S+Constant (NICE!)

• 10732 UVA (2) //Brute-force passes .. just don't trust them O(N^2)

• 10748 UVA (5) //VERY Nice (knights have K^2 moves not 8^K)

• https://codeforces.com/contest/818/problem/D (4) //NICE for each 'A' check all remaining (max SQRT)

• https://codeforces.com/contest/834/problem/E (5) //NICE — hard to imple: all 11122...999 OK

• https://www.spoj.com/problems/JHAGIRLS/ (4) //Efficient — or store output in array

• https://codeforces.com/contest/846/problem/B (3) //Brute-force

• https://www.spoj.com/problems/ALONE/ (4) //Generate everything <10^15 [NICE]

• https://codeforces.com/contest/861/problem/B (3) //Check all floor-sizes

• https://www.spoj.com/problems/RRANGE/ (3) //Compare all queries agains all updates + GAUSS

• https://codeforces.com/contest/598/problem/B (3) //Treap works too ;-)

• https://www.spoj.com/problems/AMR10I/ (4) //Can be solved with brute-force with dp

• https://codeforces.com/contest/868/problem/C (4) //Brute-force (fixet at most 6 each bits)

• https://codeforces.com/contest/868/problem/D (5) //NICE: Maximal K is low (I assumed 15)

• https://codeforces.com/contest/31/problem/C (2) //LOW-Constaints: N^2

• https://codeforces.com/contest/32/problem/D (3) //Simply try all possibilities

• https://codeforces.com/contest/876/problem/C (3) //Try N and ~100 lower

• https://codeforces.com/contest/44/problem/B (2) //N^2 works fine

• https://codeforces.com/gym/101840 E //NICE

• DCP-176: Motku2 [DevSkills]

• https://codeforces.com/contest/715/problem/C 9

• https://codeforces.com/contest/741/problem/D 8

• 13164 UVA (7)

• https://codeforces.com/contest/752/problem/F 5

• https://codeforces.com/contest/766/problem/E 6

• https://codeforces.com/contest/833/problem/D 7 //Very nice — hard (thinking + imple) + FW

• https://www.spoj.com/problems/HOLI/ (4) //VERY NICE: 2*Distances from centroids

• https://codeforces.com/contest/741/problem/C 6

• 11331 UVA (4)

• https://codeforces.com/contest/664/problem/D 4

• https://www.spoj.com/problems/ADATEAMS/

• https://www.spoj.com/problems/ADASUM/

• https://codeforces.com/gym/101808/problem/F (3) //[EASY]][FACTORIAL]

• https://codeforces.com/problemset/problem/364/A (4) //[NICE][STL-or-sorting][IF]

• https://codeforces.com/contest/145/problem/D (7) //[VERY NICE][SET][OBSERVATION][BS][BIG]

• https://codeforces.com/contest/909/problem/B (3)

• https://codeforces.com/contest/131/problem/C (3) //[EASY][BRUTE-FORCE][COMB-NUMBERS]

• https://codeforces.com/contest/131/problem/B (2) //[EASY]

• https://codeforces.com/contest/129/problem/E (5) //[NICE][COMB-NUMBERS]//Observe

• https://codeforces.com/contest/111/problem/D (5) //[COMB-NUMBERS][POWER][VERY NICE][DP]

• https://codeforces.com/contest/895/problem/D (4) //[COMB-NUMBERS][OPTI]

• https://codeforces.com/contest/893/problem/E (5) //[COMB-NUMBERS][NUMBER-THEORY]

• https://codeforces.com/contest/894/problem/B (3) //try without last row

• https://codeforces.com/contest/890/problem/E (6) //Permutations

• https://codeforces.com/contest/52/problem/B (4) //[NICE][PREPROCESS][ROTATION]

• 3917 //Grid tiling [fancy approximation fomula]

• https://codeforces.com/contest/760/problem/F

• https://devskill.com/CodingProblems/ViewProblem/61

• https://devskill.com/CodingProblems/ViewProblem/255

• UVA 10918

• UVA 12576

• UVA 1118 //Parity

• https://www.spoj.com/problems/HLP_RAMS/ //Comb parity

• Project Euler #78: Coin partitions //Partition function

• https://www.spoj.com/problems/MAIN75/ //DP #of trees

• 12001 UVA (3)

• 12034 UVA (4)

• 11719 UVA (5)

• 11798 UVA (5)

• 11282 UVA (4) //dearrangement

• 11174 UVA (4)

• https://codeforces.com/contest/666/problem/C 7

• https://www.spoj.com/problems/JOKER1/ 3 prod(Ai-i)

• https://www.spoj.com/problems/ANTP/ //4

• https://codeforces.com/contest/645/problem/E (5) //formula: A[i]=Sum(A)+1

• https://www.spoj.com/problems/SPCE/ (5) // N^{K-2}*Prod(comp_size)

• https://codeforces.com/contest/785/problem/D (5) // F'(' C"(+)-1","("

• 13184 UVA (3)

• https://codeforces.com/contest/816/problem/D (5) // Observation

• 13214 (4) //OEIS? : C(N+M-2,N-1)

• https://codeforces.com/contest/844/problem/B (2) //Easy — pro prvaky

• https://www.spoj.com/problems/JOSWAP/ (3) //Frequence array

• https://www.spoj.com/problems/UCV2013E/ (4) //NICE&EASY: Choose steps to direction

• https://www.spoj.com/problems/PARCARD1/ (4) //Partition function (raw)

• https://www.spoj.com/problems/GOODB/ (2) //Easy (NICE): Choose [order]

• https://www.spoj.com/problems/LOOPEXP/ (4) //A000254/N!

• https://www.spoj.com/problems/DTPOLY/ (5) //DP might work too

• https://www.spoj.com/problems/DTPOLY2/ (7) //Harder version of above (NICE but hell)

• https://www.spoj.com/problems/HC12/ (3) //NICE — Sort + C(i,K-1)*A[i]

• https://www.spoj.com/problems/STONE2/ (4) //NICE — Mostly DP [INVERSION][FACTORIAL]

• https://www.spoj.com/problems/MAIN8_D/ (5) //NICE — Suffixes/Prefixes (same add 2^i)

• https://www.spoj.com/problems/ITRIX_E/ (4) //VERY NICE — #Nonattacking 2-queens

• https://www.spoj.com/problems/MAXSUB/ (3) //NICE — Subsets made of zeroes

• https://www.spoj.com/problems/SKYLINE/ (3) //Catalan numbers [weird modulo — care]

• https://codeforces.com/contest/26/problem/D (5) //Division of two combintion numbers [NI:/]

• https://codeforces.com/contest/872/problem/E (6) // Prod:Sum(C(DistLines,CompSize))

• https://codeforces.com/contest/922/problem/F (6) //[NICE][MATH][GREEDY]

• https://codeforces.com/contest/916/problem/C (3) //Graph construction

• https://codeforces.com/contest/148/problem/B (3) //[SIMULATION](math or bs)

• https://codeforces.com/contest/909/problem/F (6) //[VERY NICE][BITS]

• https://codeforces.com/contest/141/problem/C (4) //[NICE][BRUTE-FORCE]

• https://codeforces.com/contest/907/problem/D (5) //[VERY NICE][RANDOM]

• https://codeforces.com/contest/124/problem/C (3) //[NICE][SIEVE]

• https://codeforces.com/contest/125/problem/C (4) //[NICE][C(N,2)]

• https://codeforces.com/contest/902/problem/C (4) //[NICE]//Tree isomorphism

• https://codeforces.com/contest/112/problem/C (3) //[GREEDY]//Max + 1s

• https://codeforces.com/contest/110/problem/B (2) //Easy modulo

• https://codeforces.com/contest/894/problem/C (3) //[VERY NICE] //AiAiGCD

• https://codeforces.com/contest/97/problem/B (4) //NICE — Walls in middles [D&C]

• https://codeforces.com/contest/85/problem/A (3) //MODULO / SHIFT

• https://codeforces.com/contest/81/problem/D (3) //NICE — MAX(N/2) — even/odd

• https://codeforces.com/contest/63/problem/D (3) //NICE[GO BY LINES][4 WAYS B/D ODD/EVEN]

• https://codeforces.com/contest/42/problem/C (4) //Constructive works too but random is fine :)

• https://codeforces.com/contest/43/problem/D (3) //NICE — Easy to see [implementation]

• https://codeforces.com/contest/53/problem/C (2) //EASY [B/E Alternate]

• https://codeforces.com/contest/877/problem/C (3) //NICE 3*Alternative

• https://codeforces.com/contest/802/problem/H (6) //We can do "N+k" by adding a letter p+k*x+u+xx

• https://codeforces.com/contest/12/problem/E (5) //g[i][j]=1+(i+j)%(N-1) [+/-]

• https://codeforces.com/contest/22/problem/C (4) //Start and then clique without v (+ random)

• https://codeforces.com/contest/26/problem/C (5) //make EvenEven: do by 22 fields

• https://codeforces.com/contest/41/problem/E (4) //[NICE][CN/2,N/2]

• https://codeforces.com/contest/78/problem/B (2) //NICE — last 3 and then rest in modulo

• https://codeforces.com/contest/109/problem/D (5) //[NICE][BACK-POINTERS][SIMULATION][SORT]

• https://www.spoj.com/problems/ADASEA/

• https://www.urionlinejudge.com.br/judge/en/problems/view/2732 (3) //Easy flood

• https://codeforces.com/contest/920/problem/E (5) //[NICE][DFS][SET] //Or clever random

• https://codeforces.com/contest/915/problem/D (4) //[VERY NICE][CYCLES DETECTION (ORIENTED)]

• https://www.spoj.com/problems/CTTC/ (3) //[EASY][GRAPH-RECONSTRUCTION]

• 7951 — Islands (3) //[NICE]Flood-Fill

• https://codeforces.com/contest/901/problem/D (7) //Observations / Tree reduction

• https://codeforces.com/contest/902/problem/B (3) //No dfs needed

• https://codeforces.com/gym/101630 {C}(4) //[NICE][SCC]

• https://codeforces.com/gym/101620 {J}(4) //DFS + multiples of divisors

• https://codeforces.com/contest/120/problem/F (3) //Width of tree

• 7606 — Percolation (3) //Dfs on grid [EASY]

• https://codeforces.com/contest/116/problem/C (2) //[DEPTH]

• 8080 — Christmas Tree (3) //[SIMPLE][NICE]

• 6584 — Escape (8) //[VERY VERY VERY NICE][COMPRESSION][MERGING] //Hard but I recommend this one!!

• 6590 Digraphs (4) //[VERY NICE][CYCLES][DP][IDEA]

• https://codeforces.com/contest/893/problem/C (3) //Minimum from each connected component

• https://codeforces.com/contest/884/problem/C (3) //[EASY][PERMUTATIONS][SORTING]

• https://codeforces.com/contest/883/problem/G (4) //Greedy picking

• https://codeforces.com/contest/60/problem/B (3) //3D Flood-Fill [NICE][EASY]

• https://codeforces.com/contest/60/problem/C (4) //[VERY NICE][BF]//Not many real possibilities

• https://devskill.com/CodingProblems/ViewProblem/3

• https://devskill.com/CodingProblems/ViewProblem/17

• https://devskill.com/CodingProblems/ViewProblem/118 //Kind-of

• 657 — The die is cast [UVA]

• 12186 UVA (3)

• https://codeforces.com/contest/734/problem/E (5)

• https://codeforces.com/contest/727/problem/A (3)

• https://codeforces.com/contest/723/problem/E (6)

• https://codeforces.com/contest/709/problem/E (6)

• https://codeforces.com/contest/710/problem/E (4)

• https://codeforces.com/contest/758/problem/E (8)

• 11323 UVA (5)

• https://codeforces.com/contest/760/problem/B (3)

• https://codeforces.com/contest/761/problem/E (6)

• https://codeforces.com/contest/638/problem/B (3) //connect cons. letters

• https://codeforces.com/contest/638/problem/C (4) //greedy idea — easy

• https://codeforces.com/contest/638/problem/D (5) //spec-DAG articulatin

• https://codeforces.com/contest/767/problem/C (4)

• https://codeforces.com/contest/781/problem/C (5)

• https://codeforces.com/contest/794/problem/D (5) //NICE! Right done dfs

• https://codeforces.com/contest/802/problem/K (5) //Slightly DP-like (NICE) TREE

• https://codeforces.com/contest/813/problem/C (3) //Simply 2 DFS: NICE + EASY

• https://codeforces.com/contest/841/problem/D (4) //DFS while tracking "next"

• https://codeforces.com/contest/845/problem/G (5) //Keep track of cycles

• https://codeforces.com/contest/844/problem/E (5) //Post-Order → line, Connect i → N-2: star

• https://www.spoj.com/problems/CAC/ (5) //VERY NICE! — Find all cycles in cactus

• https://codeforces.com/contest/849/problem/C (3) //State search by gauss

• https://codeforces.com/contest/846/problem/E (5) //NICE: DFS + some overflow logic

• https://www.spoj.com/problems/KOZE/ (3) //NICE: Floods

• https://www.spoj.com/problems/RIOI_2_3/ (4) //DFS /OR/ BFS /OR/ DSU [NICE][EASY][BF]

• https://www.spoj.com/problems/MAKEMAZE/ (3) //EASY — Simple dfs on grid

• https://codeforces.com/contest/861/problem/F (5) //VERY NICE: Modify dfs tree so it remains connected

• https://www.spoj.com/problems/GHOSTS/ (3) //NICE — must remain dag after each QR

• https://www.spoj.com/problems/AMR10J/ (5) //VERY NICE! — DFS+DP [DAG with cycles]

• https://codeforces.com/contest/24/problem/A (2)//NICE [DFS-ON-CYCLE]

• https://codeforces.com/contest/29/problem/C (3) //Find begining/end of line (graph)

• https://codeforces.com/contest/29/problem/D (4) //Tree [implementation][simulation]

• https://www.spoj.com/problems/PR003004/ (4) //Simple digits count

• https://codeforces.com/contest/770/problem/B (3) //max num max digsum

• https://www.spoj.com/problems/ADATRIP/

• https://codeforces.com/gym/101666 D //[NICE]

• https://codeforces.com/contest/144/problem/D (4) //[VERY NICE][IFS]

• https://www.spoj.com/problems/ADRABR/ (3) //Classical dijkstra — bad statement

• https://codeforces.com/contest/141/problem/D (5) //[NICE]Many Conditions

• 6583 Subway (5) //[NICE]//Not exactly dijkstra by slightly similar [IMPLEMENTATION]

• 3850 [LA]

• Gym 100625D [2013 Benelux Algorithm Programming Contest (BAPC 13)]

• UVA 12950

• Gym 100753A [2015 German Collegiate Programming Contest (GCPC 15) + POI 10-T3]

• UVA 13030

• UVA 1027

• UVA 11377

• https://codeforces.com/problemset/problem/843/D

• 11813 UVA

• Gym 101242B [2016 ACM-ICPC World Finals] //+DP

• Gym 100923B [2015 ACM National Contest Romania — Round 1]

• UVA 11833

• https://www.spoj.com/problems/EZDIJKST/en/

• LightOJ 1019

• UVA 13010 //+TS

• 2819 [LA]

• UVA 12144

• https://codeforces.com/contest/716/problem/D 7

• 12047 UVA 4

• 11514 UVA 4

• https://codeforces.com/contest/757/problem/F 7

• 11338 UVA (4)

• 11374 UVA (4)

• 11097 UVA (4) //Divide to N*1000 nodes and go!

• 13172 UVA (5) //6*DJ per query + permutations

• 10816 UVA (4) //Easy Linear-Search by answer + DJ with path

• https://codeforces.com/contest/827/problem/F 7 //Very nice — Even&Odd

• https://www.spoj.com/problems/DELIVER/ (5) //Normalize coordinates + Optimalize

• https://www.spoj.com/problems/CCHESS/ (4) //Dijkstra as knight

• 8257 — Factor-Free Tree LA //[VERY VERY NICE][PRIMES][FACTOR]

• https://www.urionlinejudge.com.br/judge/en/problems/view/1683 (4) //RAW histogram

• https://codeforces.com/contest/817/problem/D (5) //Very nice NlogN

• https://www.spoj.com/problems/DYNACON2/ (8) //Lesser hell — offline Nlog(N) /or/ NlogN^2

• https://codeforces.com/contest/876/problem/F (5) //VERY NICE — Find greatest + next/back functions

• https://codeforces.com/gym/101840 D //[EVENTS][NICE]

• https://codeforces.com/gym/101741/problem/F (6) //[NICE][PROBABILITY][GCD]

• https://www.spoj.com/problems/FRNDAM/ (3) //Simply find sum of all divisors (low constraints)

• https://codeforces.com/contest/920/problem/F (5) //[NICE][FAST FALL][SET][DIVISORS]

• 7726 A Simple Math Problem (4) //TLE if naive (consider only divisors)

• https://codeforces.com/contest/112/problem/D (4) //[NICE] Last-position [FACTOR]

• https://codeforces.com/contest/75/problem/C (3) //[NICE][BS]

• LightOJ 1068

• LightOJ 1134

• Project Euler #95: Amicable chains

• NAJ0001 — Divisible Number Sum [SPOJ]

• https://www.spoj.com/problems/LCMSUM/

• https://www.hackerrank.com/contests/101hack38/challenges/easy-gcd-1/problem

• UVA 13085

• https://www.spoj.com/problems/CDRSANJ/

• https://www.spoj.com/problems/DIVSEQ/

• UVA 12154

• UVA 13058

• https://www.spoj.com/problems/EC_DIVS/

• https://www.codechef.com/problems/CHEFKEY

• https://codeforces.com/problemset/problem/671/C

• Gym 101411G [2009-2010 ACM-ICPC, NEERC, Western Subregional Contest]

• https://codeforces.com/problemset/problem/831/F

• https://codeforces.com/problemset/problem/839/D

• 12934 — Factorial Division [UVA]

• UVA 10880

• https://www.spoj.com/problems/PSTR/

• https://codeforces.com/problemset/problem/27/E

• [LA] 3014

• UVA 12843

• https://www.urionlinejudge.com.br/judge/en/problems/view/1164

• https://codeforces.com/problemset/problem/803/F

• 10892 — LCM Cardinality

• https://www.spoj.com/problems/GCDEX/

• https://www.spoj.com/problems/INVDIV/

• 13083 — Yet another GCDSUM //ll

• https://www.spoj.com/problems/IITKWPCF/ //ll

• UVA 13185

• UVA 13194

• UVA 11388

• https://www.spoj.com/problems/SAS002/

• 12425 — Best Friend

• https://codeforces.com/problemset/problem/703/E

• https://www.hackerearth.com/problem/algorithm/harry-gets-into-infy/

• UVA 10830 //SUM

• https://www.spoj.com/problems/DIVSUM/en/ //SUM

• https://www.spoj.com/problems/AFS/ //SUM

• UVA 11526 //SUM

• https://www.spoj.com/problems/ADAZOO/

• https://www.spoj.com/problems/ADASEQEN/

• https://www.spoj.com/problems/ADAMOLD/

• https://www.spoj.com/problems/ADASALE/

• https://codeforces.com/gym/101889 E

• https://codeforces.com/gym/101808/problem/D (7) //[NICE][OPTIMISATION][EFFICIENCY]

• https://codeforces.com/gym/101666 I

• https://codeforces.com/gym/101840 A //Doubles

• DevSkills 475: Bunty's Xor Game (4) //[BITS][GAME THEORY]

• https://www.devskill.com/CodingProblems/ViewProblem/489 (5) //[NICE][FACTORISATION]

• DevSkills 534 (4) //[BITSET][COMBINATIONS]

• https://codeforces.com/gym/101650 D //Not hard — more coding + printing

• 13286 — Ingredients (4) //[NICE][DAG] Classical

• 8299 — Bricks (5) //[NICE][COMBINATORICS][SORTING]

• https://codeforces.com/contest/934/my (4) //Subsequence

• https://codeforces.com/contest/922/problem/E (5) //find max mana

• https://codeforces.com/contest/920/problem/D (4) //[NICE][KNAPSACK-MODULO][GREEDY]

• https://codeforces.com/contest/919/problem/D (4) //[NICE][DFS][CYCLE][DAG]

• https://codeforces.com/contest/914/problem/C (3) //[DIGITS][BINARY]

• https://codeforces.com/contest/913/problem/E (5) //[NICE][EXPRESSION]

• https://codeforces.com/contest/148/problem/E (5) //[DP][PREFIX SUM][GREED]

• https://www.spoj.com/problems/PALMKR/ (4) //Classical palindrome + print + lexicography

• https://codeforces.com/contest/146/problem/E (5) //[NICE][COMBINATORICS][OBSERVATION]

• https://codeforces.com/contest/909/problem/C (4) //[NICE][CLASSICAL][EASY]

• 7785 — m-ary Partitions (4) //Combinatorics

• https://codeforces.com/contest/133/problem/E (4) //[IMPLEMENTATION]

• https://codeforces.com/contest/126/problem/D (5) //[NICE]//Decomposet DP//Own hash-map

• https://codeforces.com/contest/910/problem/B (3) //Or many other ways

• 6154 RNA Secondary Structure (5) //[NICE] Unoptimal might work too

• https://arc087.contest.atcoder.jp/tasks/arc087_b (4) //[VERY NICE][OBSERVATION]

• https://codeforces.com/contest/903/problem/F (5) //[VERY NICE][BITMASK][BRUTE]

• https://codeforces.com/contest/903/problem/A (2) //Easy knapsack-like // Low constraints

• https://codeforces.com/contest/900/problem/E (4) //[NICE]//Patter-match: FFT or KMP or Brute-Force

• https://codeforces.com/contest/118/problem/D (3) //[COMBINATORICS][LOW-CONSTRAINTS]

• https://codeforces.com/contest/115/problem/E (5) //[VERY NICE][SEGMENT TREE]

• https://codeforces.com/contest/116/problem/D (3) //CLASSICAL[LOW-CONSTRAINTS]

• 10128 Queue (uva) (4) //One possibility is bitmask — second combinatorics

• https://codeforces.com/contest/110/problem/C (3) //[EASY]// Greedy/math works too

• 8078 — Bracket Sequence (4) //[VERY NICE][DP-LINKS]

• https://codeforces.com/contest/106/problem/C (3) //[NICE][EASY]

• https://codeforces.com/contest/895/problem/C (4) //[NICE]

• 8024 Stack Construction (4) //[NICE] Palindromic style — but not exactly

• 7708 — Cubes (6) //[MATH]

• https://codeforces.com/contest/888/problem/F (6) //[NICE][FLAG]

• https://www.spoj.com/problems/ACQUIRE/ (5) //[NICE][CH-OPT]

• https://codeforces.com/contest/319/problem/C (6) //[NICE][CH-OPT]

• https://www.spoj.com/problems/NKLEAVES/ (5) //[NICE][DC]

• https://codeforces.com/contest/76/problem/D (4) //[BITS][OVERFLOW]

• https://codeforces.com/contest/73/problem/C (4) //[NICE][EASY][TRY-ALL-LETTERS]

• https://codeforces.com/contest/67/problem/C (4) //[NICE][LEAVENSTEIN]

• https://codeforces.com/contest/67/problem/A (3) //[EASY][PRINTING][OTHER POSSIBLE WAYS]

• https://codeforces.com/contest/55/problem/D (5) //[NICE][DIGITS][EFFICIENT]

• https://codeforces.com/contest/56/problem/D (4) //String modification + printing [NICE]

• https://codeforces.com/contest/58/problem/E (6) //[NICE][IMPLEMENTATION]

• UVA 12181

• https://devskill.com/CodingProblems/ViewProblem/21

• https://devskill.com/CodingProblems/ViewProblem/37

• https://devskill.com/CodingProblems/ViewProblem/71

• https://devskill.com/CodingProblems/ViewProblem/103

• https://devskill.com/CodingProblems/ViewProblem/107

• https://devskill.com/CodingProblems/ViewProblem/115

• https://devskill.com/CodingProblems/ViewProblem/126

• https://devskill.com/CodingProblems/ViewProblem/131

• https://devskill.com/CodingProblems/ViewProblem/134

• https://devskill.com/CodingProblems/ViewProblem/174

• https://devskill.com/CodingProblems/ViewProblem/186

• https://devskill.com/CodingProblems/ViewProblem/201

• https://devskill.com/CodingProblems/ViewProblem/338

• https://devskill.com/CodingProblems/ViewProblem/368

• https://devskill.com/CodingProblems/ViewProblem/392

• https://devskill.com/CodingProblems/ViewProblem/399

• https://www.hackerrank.com/contests/world-codesprint-5/challenges/mining //Opti

• UVA 12915 //Opti

• UVA 12524 //Opti

• https://codeforces.com/problemset/problem/631/E //CH

• https://devskill.com/CodingProblems/ViewProblem/6

• https://devskill.com/CodingProblems/ViewProblem/11

• 11552 UVA (3)

• 12172 UVA (3)

• 4507 LA (5)

• 4510 LA (5) [+ geometry]

• 12181 UVA (6)

• https://codeforces.com/contest/729/problem/F 6

• https://codeforces.com/contest/735/problem/E 9

• https://codeforces.com/contest/731/problem/E 5

• 12030 UVA (4)

• https://codeforces.com/contest/721/problem/E 7

• https://codeforces.com/contest/742/problem/D 4

• 12040 UVA (5)

• https://codeforces.com/contest/712/problem/D 5

• 13162 UVA (6)

• https://codeforces.com/contest/743/problem/E 6

• 11908 UVA (3)

• 11932 UVA (4)

• https://codeforces.com/contest/745/problem/E (7)

• 11806 UVA (4)

• https://codeforces.com/contest/747/problem/F (5)

• 11843 UVA (4)

• https://codeforces.com/contest/752/problem/E (5)

• https://codeforces.com/contest/703/problem/E (7)

• 11753 UVA (4)

• 11725 UVA (5)

• https://codeforces.com/contest/722/problem/E (9)

• https://codeforces.com/contest/760/problem/F (8)

• 11795 UVA (3)

• 11654 UVA (4)

• 11523 UVA (5)

• 11404 UVA (4)

• 11432 UVA (4)

• 11451 UVA (4) //C==20 mistake in statement

• 11301 UVA (4)

• https://codeforces.com/contest/762/problem/D 5

• 11361 UVA (4) //digit DP

• 11365 UVA (7)

• 11391 UVA (4) //easy+implementation

• 11394 UVA (3)

• 11218 UVA (2)

• 11125 UVA (4) //slightly implementation

• 11076 UVA (3)

• 11081 UVA (4) //3 string subsequences (beware of fail)

• https://codeforces.com/contest/678/problem/E (5) //bitset dp + probability

• https://codeforces.com/contest/766/problem/C (4)

• https://codeforces.com/contest/667/problem/C (3)

• https://www.spoj.com/problems/MOVIFAN/ (3)

• https://www.spoj.com/problems/ORDSUM23/ (3)

• https://www.spoj.com/problems/DIVSEQ/ (4) //N^3 (but better...) works fine

• https://codeforces.com/contest/633/problem/F (7) //Tree dp

• https://www.spoj.com/problems/ADJDUCKS/ (4) sort + pick 2-3 continous O(N)

• https://www.spoj.com/problems/JLNT/ (4) //pick 0 or 2 | 1e3*5e3

• https://www.spoj.com/problems/TPCPALIN/ (5) //500^3 works (3rd countable)

• https://www.spoj.com/problems/COLORSEG/ (4) //50^4==OK 50^4log(N)=TLE NICE

• https://www.spoj.com/problems/POWERCAR/ (3) //1e31e32 — follow rules

• https://www.spoj.com/problems/INGRED/ (5) //TSP-like [reduce + go]

• https://www.spoj.com/problems/BADXOR/ (4) //classical subsets

• https://www.spoj.com/problems/SPCO/ (5) //64642 DP {OPT: prime O(1) + clear only half}

• https://www.spoj.com/problems/WAYHOME/ (5) //NICE: 1) 1*1 b)12,1,**,2

• https://www.spoj.com/problems/NFURY/ (2) //Minimal sum of squares

• https://www.spoj.com/problems/GDIL/ (3) //combinatorics

• https://codeforces.com/contest/791/problem/D (5) //Tree

• https://codeforces.com/contest/791/problem/E (6) //V,K,X — pick any

• https://codeforces.com/contest/789/problem/C (3)

• 13176 (4) //N^6

• 13179 (5) //NICE [Ath][Bth][TimeDiff]

• https://codeforces.com/contest/796/problem/E (6) //NICE: NPK*K (WC can't happen!)

• https://codeforces.com/contest/797/problem/E (4) //NICE: Almost BF-able (but care of low K)

• https://codeforces.com/contest/793/problem/D (3) //NICE & EASY: begin/end/actual/USED

• https://codeforces.com/contest/803/problem/E (4) //State search — many IF's (EASY)

• https://codeforces.com/contest/805/problem/F (7) //NICE: DP on tree + fast BF + hack

• https://codeforces.com/contest/808/problem/E (5) //NICE!

• https://codeforces.com/contest/811/problem/C (4) //Precalculate + DP (greedy thinking)

• 10817 UVA 4 //Easy but slightly implementation

• 10859 UVA 4 //Nice — on tree .. but for a reason small constrains

• 10898 UVA 4 //Hash is lesser than 1e6 .. try everything

• https://codeforces.com/contest/812/problem/B (3) //Not only DP, yet imho easiest ..many spec cases

• https://codeforces.com/contest/813/problem/D (5) //VERY VERY NICE — N*N (none picked between a/b)

• https://codeforces.com/contest/814/problem/E 5 //VERY NICE — Harder imple: Combinatorics

• https://codeforces.com/problemset/problem/816/E (6) //NICE — Tree (hard 2C complexity)

• https://codeforces.com/contest/837/problem/D (5) //NICE — yet kinda pain [must be iterative]

• https://www.spoj.com/problems/AUT/ (4) //NICE — K is interesting ~ at most 1600

• https://www.spoj.com/problems/GNYR04C/ (3) //Easy — Nice idea [Big→ Low approach]

• https://www.spoj.com/problems/TIEROPE/ (4) //Process 2*L ~ otherwise pick BIG

• https://www.spoj.com/problems/IITKWPCE/ (4) //Palindromes [efficiency!] — NICE!

• IITKWPCD SPOJ (4) //+Slightly geometry

• UVA 1496 //[Steiner's Tree] Very Nice (8)

• https://www.spoj.com/problems/LKS/ (3) //Classical knapsack

• https://www.spoj.com/problems/UOFTAE/ (3) //Easy & Sympatic DP

• https://www.spoj.com/problems/DCOWS/ (4) //Very NICE (sort + GO)

• https://www.spoj.com/problems/FARIDA/ (3) //Easy & Sympatic ((u+1) | Price+(u+2))

• https://www.spoj.com/problems/AU7_5/ (2) //EASY: dyn(n-1)+dyn(n-k-1)

• https://www.spoj.com/problems/NAIVELOK/ (4) //NICE [depalindromisation]

• https://codeforces.com/contest/846/problem/C (4) //With print

• https://www.spoj.com/problems/CNT_LUCK/ (4) //Number (binary) dp [NICE] {ull care 0-1}

• https://www.spoj.com/problems/MAY99_4/ (3) //Almost combinatoric Sub and 0/1,1/0

• https://www.spoj.com/problems/GEEKOUNT/ (4) //Number dp

• https://www.spoj.com/problems/MUTDNA/ (4) // N*2 (turned?) [not sure if grd poss.]

• https://www.spoj.com/problems/RIOI_3_2/ (5) //VERY NICE (easy imple — Number Theory thinking)

• https://www.spoj.com/problems/MAXWOODS/ (3) //NICE [EASY][GRID]

• https://www.spoj.com/problems/DIEHARD/ (3) //Easy — prolly solvable by greedy (but dp is easier)

• https://www.spoj.com/problems/DCEPC810/ (4) //VERY VERY NICE — Subsequence 2pointers+2bools

• https://www.spoj.com/problems/EQ2/ (4) //NICE: Digit + Carry (from back) — iff-party

• https://www.spoj.com/problems/DCEPC501/ (3) //NICE & EASY

• https://www.spoj.com/problems/NUMTSN/ (4) //NICE — Thinking or Opti

• https://www.spoj.com/problems/GONE/ (4) //NICE & EASY [digits]

• https://www.spoj.com/problems/RAONE/ (4) //NICE & EASY [digits] — almost similar as above

• https://www.spoj.com/problems/STRSEQ/ (4) //VERY VERY NICE — Next-Function

• https://www.spoj.com/problems/MYQ8/ (4) //VERY NICE — 3x3 tic-tac-toe [implementation]

• https://codeforces.com/contest/859/problem/C (3) //Easy+Sympathic [PrefixSumOptional]

• https://codeforces.com/contest/859/problem/D (4) //NICE [Probabilities]

• https://www.spoj.com/problems/UNICA/ (4) //VERY NICE [Posibilities][Print][Classical]

• https://www.spoj.com/problems/KOPC12H/ (4) //NICE Digit-DP

• https://www.spoj.com/problems/DRACULA/ (4) //NICE Digit-DP (Both sides) — iterate by sum

• https://www.spoj.com/problems/ABCPATH/ (3) //DP over dfs (maybe without dp works too?)

• https://www.spoj.com/problems/BEHAPPY/ (2) //Easy one — low constraints

• https://www.spoj.com/problems/STRCOUNT/ (4) //No input (over bits)

• https://codeforces.com/contest/855/problem/B (2) //prolly not even necessary

• https://codeforces.com/contest/855/problem/C (4) //dp on tree

• https://codeforces.com/contest/855/problem/E (5) //VERY NICE — Digits & Bitmask & Query (learning!)

• https://www.spoj.com/problems/PAINTWAL/ (6) //VERY NICE — Imho hard (opti could beat)

• https://www.spoj.com/problems/ADFRUITS/ (3) //Very simple (substring == subsequence)

• https://www.spoj.com/problems/MAIN113/ (2) //NICE but somehow too low constraints

• https://www.spoj.com/problems/MAIN112/ (4) //NICE — Bitmask

• https://codeforces.com/contest/864/problem/E (5) //VERY NICE — Sort

• https://www.spoj.com/problems/NOVICE63/ (4) //NICE -On digits (binary)

• https://www.spoj.com/problems/TUG/ (3) //NICE + Observation {N>100 == YES}

• https://www.spoj.com/problems/DOMINO1/ (4) //Used map to solve it

• https://www.spoj.com/problems/NY10E/ (2) //Easy dp

• https://www.spoj.com/problems/MAIN72/ (3) //Easy knapsack

• https://www.spoj.com/problems/NOVICE43/ (2) //Unbelievably low constraints

• https://codeforces.com/contest/598/problem/E (4) //N^5 strategy works fine [VERY NICE]

• https://www.spoj.com/problems/CHAIR/ (3) //Maybe combinatorics too?

• https://www.spoj.com/problems/ACPC10D/ (3) //NICE — DAG traversal

• https://www.spoj.com/problems/CPCRC1C/ (4) //Digits dp (return pair)

• https://www.spoj.com/problems/BORW/ (3) //Inc+Dec sequence (small array)

• https://codeforces.com/problemset/problem/16/E (5) //Bitmask [NICE]

• https://codeforces.com/problemset/problem/18/E (5) //VERY NICE {no need for second iteration}

• https://codeforces.com/contest/2/problem/B (5) //NICE — 2/5 are in-fact independent

• https://codeforces.com/contest/4/problem/D (3) //Classical [FW works too] XY > xy

• https://codeforces.com/contest/6/problem/D (4) //NICE (N^4)

• https://codeforces.com/contest/321/problem/E (7) //VERY NICE — D&C Trick

• https://codeforces.com/contest/868/problem/F (8) //VERY VERY NICE D&C Trick — With MO Principal

• https://codeforces.com/contest/8/problem/C (5) //NICE — Masks [N*2^N]

• https://codeforces.com/contest/868/problem/E (8) //VERY NICE — HARD — on tree

• https://codeforces.com/contest/10/problem/D (4) //LCIS [NICE]

• https://codeforces.com/contest/13/problem/C (5) //NICE [sorting][only elements from array]

• https://codeforces.com/contest/17/problem/C (5) //[NICE][iterative-sparse][+idea]

• https://codeforces.com/contest/19/problem/B (4) //Knapsack (after good look)

• https://codeforces.com/contest/30/problem/C (4) //Probabilities + (slight)GEO

• https://codeforces.com/contest/31/problem/E (4) //[NICE]

• https://codeforces.com/contest/41/problem/D (4) //With printing

• https://www.spoj.com/problems/ADABRANC/

• https://codeforces.com/contest/915/problem/F (6) //[VERY NICE][SORTING]

• https://codeforces.com/contest/141/problem/E (6) //[NICE][SPANNIG TREE]

• 7903 — Pandaria (7) //[VERY NICE][DSU][SORTING][MERGE][DFS]

• https://codeforces.com/contest/110/problem/E (4) //[NICE][COMBINATORICS][TREE]

• https://codeforces.com/contest/90/problem/E (5) //[NICE][DSU-LIKE-LINKS][SIMULATION]

• https://codeforces.com/contest/87/problem/D (5) //[VERY NICE][SORTING][COMPRES][DFS]

• https://codeforces.com/contest/884/problem/E (5) //[VERY NICE][MEMORY SPARSE]

• https://codeforces.com/contest/60/problem/D (6) //[NICE][Pythagorean Triples][Gen over max!]

• UVA 10947

• UVA 12363

• LA 3833

• https://codeforces.com/problemset/problem/742/D //+DP

• UVA 10178

• https://codeforces.com/contest/723/problem/F 7

• 13153 UVA (5)

• 13169 UVA (3)

• 11987 UVA (3)

• 11474 UVA (4)

• https://www.spoj.com/problems/BTCODE_G/

• https://codeforces.com/problemset/problem/691/D

• Gym 101174K [2016-2017 ACM-ICPC Southwestern European Regional Programming Contest (SWERC 2016)]

• UVA 10583

• LightOJ 1003

• https://codeforces.com/problemset/problem/731/C

• UVA 793

• UVA 11966

• https://www.codechef.com/problems/COZIC

• 3939 [LA]

• UVA 11503

• https://codeforces.com/problemset/problem/755/C

• UVA 1395

• https://codeforces.com/contest/687/problem/D 6

• https://codeforces.com/contest/680/problem/E 7 //+precalculation/brute force

• https://codeforces.com/contest/766/problem/D 5

• https://www.spoj.com/problems/LEXSTR/ (3) //Nice na stringu

• https://codeforces.com/contest/805/problem/C 3 //NICE (dijkstra like :P)

• https://www.spoj.com/problems/IITKWPCI/ (3) //VERY NICE

• https://www.spoj.com/problems/FRNDCIRC (3) //Classical DSU (NICE for practice)

• https://www.spoj.com/problems/FOXLINGS/ (3) Easy — just renumbering

• https://www.spoj.com/problems/NITTROAD/ (4) //Process from back

• https://www.spoj.com/problems/SHAHBG/ (2) //DSU not needes (simulated by array)

• https://codeforces.com/contest/598/problem/D (3) //Can be solved with DFS too

• https://codeforces.com/contest/9/problem/E (4) //Making one big cycle

• https://codeforces.com/contest/25/problem/D (4) //Could be done linear too

• https://codeforces.com/contest/28/problem/B (4) //NICE [imho bad statement]

• https://codeforces.com/contest/876/problem/D (4) //DSU adjacent + visited

• https://codeforces.com/contest/875/problem/F (6) //NICE — Maximum cactus-forest [kruskal-like]

• https://codeforces.com/contest/907/problem/F (7) //[MAGIC]

• UVA 10299

• UVA 10990

• https://www.codechef.com/problems/SMPLSUM

• https://www.codechef.com/problems/COZIE

• https://www.spoj.com/problems/LCMSUM/

• Gym 100975F [2003-2004 Petrozavodsk Summer Training Camp, Saratov SU Contest]

• UVA 13132

• https://www.spoj.com/problems/GCDEX/

• UVA 12995

• https://www.spoj.com/problems/TIP1/

• UVA 11327

• LightOJ 1007

• https://www.spoj.com/problems/ETF/

• Project Euler #72: Counting fractions

• https://www.spoj.com/problems/DCEPCA03/

• https://www.spoj.com/problems/NAJPWG/ 4 //Gauss-Euler

• https://www.spoj.com/problems/DCEPC12G/ (5) //Do what is written there

• https://www.spoj.com/problems/INVPHI/ (5) //Inverse euler

• https://codeforces.com/gym/101650 I //[NICE][GRAPHS]// Theory is useful

• 13246 — Chained Words (4) //[NICE][LEXICOGRAPHICAL]

• UVA 10735

• https://codeforces.com/contest/789/problem/D //Adj EG + Self/everything

• https://codeforces.com/contest/21/problem/D (5) //[NICE][EulerTour+DP]

• https://codeforces.com/contest/36/problem/E (6) //VERY NICE [4odd is hardest]

• https://www.spoj.com/problems/ADAHW/ [RHO][Number Theory]

• https://www.spoj.com/problems/ADADIGIT/ [Permutations]

• UVA 13067

• Project Euler #108: Diophantine reciprocals I

• https://www.spoj.com/problems/CHGROOM/

• Gym 101370A [2009-2010 Summer Petrozavodsk Camp, Petr Mitrichev Contest 5]

• https://codeforces.com/problemset/problem/837/E

• https://www.spoj.com/problems/PSYCHOT/

• https://www.spoj.com/problems/FACTDIV/

• https://www.spoj.com/problems/NOSQ/

• https://www.spoj.com/problems/FCDC/

• https://www.spoj.com/problems/NFACTOR/

• https://www.spoj.com/problems/ABA12D/

• https://www.spoj.com/problems/PSTR/

• https://www.spoj.com/problems/AMR11E/

• https://www.spoj.com/problems/FACT1/

• https://www.spoj.com/problems/FACT2/

• https://www.hackerearth.com/problem/algorithm/gold-at-lolympics/

• 12005 UVA (7)

• 12062 UVA (6)

• 11960 UVA (3)

• https://www.spoj.com/problems/FACTCG2/ (3)

• https://www.spoj.com/problems/FACT0/ (4)

• https://codeforces.com/contest/546/problem/D 5

• https://codeforces.com/contest/222/problem/C 6

• https://www.spoj.com/problems/COMDIV/ 3

• https://www.spoj.com/problems/SINEGGS/ 3

• https://www.spoj.com/problems/BDOI16B/ 4

• https://www.spoj.com/problems/HG/ 4 //Map == OK

• 11099 UVA (3) //factor + recursion

• 13194 UVA (3) //factorize+generate /or just check

• 13191 UVA (6) //Pollard-Rho

• https://codeforces.com/contest/818/problem/E (4) // Efficient + Two Pointers

• https://codeforces.com/contest/831/problem/F (6) //MAGIC

• https://codeforces.com/contest/839/problem/D (4) // Combinatorics + IE

• https://www.spoj.com/problems/SAS002/ (5) //Find all divisors (big numbers)

• https://www.spoj.com/problems/GCDS/ (4) //Lowest unused prime

• https://www.spoj.com/problems/IITKWPCF/ (4) //Nonprime divisors of N/2

• https://codeforces.com/contest/851/problem/D (4) //Properties of GCD + factor: NICE

• https://www.spoj.com/problems/PTIME/ (3) //Low bounds — check each prime independently

• https://www.spoj.com/problems/MAIN12B/ (3) //NICE [Factorization][Sort][Unique]

• https://www.spoj.com/problems/AMR11E/ (2) //2664 is the biggest

• https://www.spoj.com/problems/GCPC11A/ (4) //Very nice — factorize + divide N by powers

• https://www.spoj.com/problems/AMR10C/ (3) //Maximum of factor-powers

• https://www.spoj.com/problems/ADABEHIVE/ [2D]

• https://www.spoj.com/problems/ADACABAA/ [2D][Sparse]

• https://codeforces.com/gym/101889 (5) //[NICE] normalize

• DevSkills-422: Double Pairs (4) //[NICE] normalize

• 7591 — Distribution Center (4) //[NICE][SORTING]

• https://codeforces.com/contest/903/problem/D (5) //[NICE][BIG]

• https://codeforces.com/contest/102/problem/D (4) //[NICE][+DP][NORMALIZE]

• https://codeforces.com/gym/101047/problem/J [2D]

• https://www.spoj.com/problems/MATSUM/ [2D]

• https://www.hackerearth.com/practice/data-structures/advanced-data-structures/fenwick-binary-indexed-trees/practice-problems/algorithm/counting-in-byteland/ [3D]

• https://devskill.com/CodingProblems/ViewProblem/300

• https://codeforces.com/contest/707/problem/E 7 [2D]

• https://codeforces.com/contest/749/problem/E 8

• https://codeforces.com/problemset/gymProblem/101055/D 5 [2D]

• 11240 UVA (4)

• https://codeforces.com/contest/459/problem/D (4) //[NICE][SWEEPING]

• https://codeforces.com/contest/61/problem/E (4) //[NICE][CLASSICAL][2*FW][NORMALIZE]

• https://codeforces.com/contest/669/problem/E 5 //fenwicks — sparse

• https://codeforces.com/contest/777/problem/E 4 //MAXIMUM

• https://www.spoj.com/problems/TULIPNUM/ 4 //inc — 1 nor+num|sum(A[B],A[E])

• https://codeforces.com/contest/799/problem/C 3 //MAX FW (but possibly easier?)

• https://codeforces.com/contest/831/problem/E 4 //MAP to get ORDER — FW == LIST

• https://www.spoj.com/problems/SAS001/ (4) //Nice — number of inversions + 2P

• https://www.spoj.com/problems/TPGA/ (4) //NICE — Lesser*(N-i-1)!

• https://www.spoj.com/problems/SGIFT/ (4) //BS works too

• https://www.spoj.com/problems/SUMSUM/ (5) //Bit-by-Bit cnt 0/1

• https://www.spoj.com/problems/AKVQLD03/ (3) //Classical fenwick — easy

• https://www.spoj.com/problems/ZIGZAG2/ (6) //Very nice — FW + BS + DP

• https://codeforces.com/contest/849/problem/E (7) //2D Fenwick / ST+TP [NICE]

• https://www.spoj.com/problems/CRAYON/ (5) //VERY NICE [2*FW — begin + end]

• https://www.spoj.com/problems/NITT8/ (4) //Norm. + Store indices in MAX-Fenwick [REVERSE] [VERY NICE]

• https://www.spoj.com/problems/DCEPC705/ (4) //NICE! Sort + Fenwick

• https://www.spoj.com/problems/DCEPC206/ (3) //NICE & EASY

• https://www.spoj.com/problems/KOPC12G/ (4) //N Fenwick trees

• https://www.spoj.com/problems/TRIPINV/ (4) //2xFenwick (triples counting)

• https://codeforces.com/contest/597/problem/C (4) //[VERY NICE] 11*Fenwick

• https://codeforces.com/contest/12/problem/D (4) //NICE [triplet-comparing][sort]

• https://www.spoj.com/problems/NARHIL/ // Sugested by ak07

• https://www.spoj.com/problems/ADAMATCH/

• UVA 12633

• 6886 — Golf Bot [LA]

• https://www.spoj.com/problems/POLYMUL/en/

• Gym 100960C [2015-2016 Petrozavodsk Winter Training Camp, Nizhny Novgorod SU Contest]

• https://www.codechef.com/problems/APRPS

• https://www.codechef.com/problems/POLYEVAL

• https://www.spoj.com/problems/TSUM/ 5

• 13182 UVA 5 //ACTG hamming

• https://codeforces.com/contest/827/problem/E (8) //MAGIC

• https://www.spoj.com/problems/MAXMATCH/ 5 //abc hamming

• https://www.spoj.com/problems/FASTFLOW/en/ //Raw (no sauce)

• https://codeforces.com/contest/78/problem/E (5) //NICE [Matching-like][+BFS]

• 4322 — Destroying the bus stations (Live Archive)

• 11380 — Down Went The Titanic (UVA) //Interesting grid problem

• 6395 — Surely You Congest (LA) //VERY NICE [slightly advanced]

• 7204 — Blood groups (LA)

• https://codeforces.com/gym/100963 (Flame of Nucleus — F)

• 11167 — Monkeys in the Emei Mountain //Also harder (imho)

• https://codeforces.com/problemset/problem/653/D (+BS)

• 13000 — VIP Treatment (+BS)

• 1242 — Necklace

• https://www.deadline24.pl/assets/problemsets/dl24.elim.2017.B.en.pdf (DEADLINE 24 problem — not sure if it can be submited :O)

• 3487 — Duopoly (Near matching)

• https://codeforces.com/problemset/problem/727/D

• https://codeforces.com/problemset/problem/704/D [Also advanced]

• 5418 — A Plug for UNIX (LA)

• 4957 — Fake scoreboard (LA) //If I remember well, other solutions was also possible

• 1155 — Power Transmission (LOJ) //(classical)

• https://www.codechef.com/problems/ROBOTDAG //Ford-Fukherson

• 10804 — Gopher Strategy (UVA)

• 11506 — Angry Programmer (UVA) //Nodes division

• 10511 — Councilling (UVA)

• 563 — Crimewave

• 1306 — The K-League (UVA)

• 1345 — Jamie's Contact Groups

• 10092 — The Problem with the Problem Setter

• Problem B. Roller Coaster Scheduling (GCJ — 2017)

• 259 — Software Allocation (UVA)

• 5905 — Pool construction (LA) //Imho harder

• 10480 — Sabotage

• https://codeforces.com/contest/808/problem/F 6 //NICE — nontrivial (max matching with bigger flows)

• https://codeforces.com/contest/847/problem/J 6 //Probably not flows — matching-like

• https://www.spoj.com/problems/ADAHOSE/ [DUAL-GRAPH]

• https://codeforces.com/contest/903/problem/G (6) //[VERY NICE][SEG-TREE][CUT]

• 3837 [LA] //Stable Marriage

• UVA 1175 //Stable Marriage

• 11594 — All Pairs Maximum Flow (UVA)

• https://www.spoj.com/problems/ADABLOOM/ //Maximum matching in general graph

• 11439 — Maximizing the ICPC //Maximum matching in general graph

• 1376 — Animal Run //Max flow on planar graph (Dual == shortest path over edges)

• 10989 — Bomb, Divide and Conquer //Stoer-Wagner — global cut

• 10724 UVA

• UVA 117

• https://codeforces.com/problemset/problem/21/D

• UVA 1198

• LightOJ 1086 //+DP

• https://www.spoj.com/problems/INGRED/ //+DP

• UVA 10048

• UVA 125

• Gym 101223C [2017 Facebook Hacker Cup, Round 1] //+DP

• LightOJ 1221

• UVA 423

• UVA 12179 //+DP

• UVA 1416

• UVA 1233

• UVA 10793

• 10099 UVA

• UVA 869

• LightOJ 1174

• https://www.spoj.com/problems/ARBITRAG/ //Other algos shall work too

• 13211 UVA (5) //NICE — FW adding states

• https://www.spoj.com/problems/ROHAAN/ (3) //Classical

• https://codeforces.com/contest/25/problem/C (4) //Adding new edges .. need FW principal

• https://codeforces.com/contest/33/problem/B (3) //NICE [dijkstra could work too]

• https://www.spoj.com/problems/ADAPOWER/

• 4956 [LA]

• https://www.spoj.com/problems/ADAGAME/ [DP]

• https://www.spoj.com/problems/ADAGAME2/

• https://www.spoj.com/problems/ADAGAME4/

• https://www.spoj.com/problems/ADAQUBIC/

• https://www.spoj.com/problems/ADAFIMBR/

• https://www.spoj.com/problems/ADAGAME5/

• https://www.spoj.com/problems/ADAXMAS/

• https://codeforces.com/gym/101808/problem/I (5) //[DP][OBSERVATION]

• https://codeforces.com/contest/919/problem/F (6) //[NICE][HARD][IMPLE][BFS][TOPO][GRAF]

• https://codeforces.com/contest/918/problem/D (4) //[NICE][DAG][DP][TREE]

• https://codeforces.com/contest/914/problem/B (3) //[NICE][EASY][OBSERVATION][PARITY]

• https://codeforces.com/contest/148/problem/D (4) //[EASY][DP][PROBABILITY]

• https://codeforces.com/contest/138/problem/D (7) //[VERY NICE][DP][OBSERVATION]

• https://arc087.contest.atcoder.jp/tasks/arc087_c (5) //[VERY NICE][TRIE][SEQUENCE]

• https://codeforces.com/contest/120/problem/E (3) //[NICE][SYMETRY][PARITY]

• https://codeforces.com/contest/88/problem/E (5) //[VERY NICE][PREFIX-XOR][NIMBERS][SQRT][MATH]

• https://codeforces.com/contest/69/problem/D (4) //[NICE][DP] Reflection can be ignored

• https://codeforces.com/contest/55/problem/C (4) //[NICE] Size of piece from border

• https://codeforces.com/problemset/problem/255/E --MEX

• https://devskill.com/CodingProblems/ViewProblem/91

• https://devskill.com/CodingProblems/ViewProblem/364

• Project Euler #96: Su Doku //Sudoku

• 11859 UVA 4

• 11863 UVA 4

• 11892 UVA 3 //Probably solved by many

• 11534 UVA 5

• https://www.spoj.com/problems/VECTAR11/ 4 //Nsqrt(N) passes [with break]

• https://codeforces.com/contest/768/problem/E (4) //NICE — Grundy

• https://www.spoj.com/problems/SYNC13C/ (4) //2*DP {maybe not seeing sth}

• https://codeforces.com/contest/787/problem/C (4)

• https://codeforces.com/contest/794/problem/C (3) //Find optimal strategy: choose back/front

• https://codeforces.com/contest/794/problem/E (5) //NICE Find stategy: Even/Odd

• https://codeforces.com/contest/812/problem/E (7) //Advanced NIM strategy

• https://www.spoj.com/problems/GAMEMVS/ (4) //Nimbers (Ai^X)<=Ai

• https://www.spoj.com/problems/PLAYGAME/ (3) //Check pattern

• https://www.spoj.com/problems/CHAOS_CC/ (4) //VERY NICE [nimbers]

• https://codeforces.com/contest/851/problem/E (5) //Very nice [nimbers] [bitset]

• https://www.spoj.com/problems/CHGROOM/ (4) //+Factorisation [NICE & Easy]: Win unless 2 prime factors

• https://www.spoj.com/problems/EALP1/ (4) //NICE ~ Possible Moves of NIM

• https://www.spoj.com/problems/GAME3/ (4) //VERY NICE — pattern watching [A145812]

• https://www.spoj.com/problems/GAME2/ (5) //VERY NICE — https://community.topcoder.com/tc?module=Static&amp;d1=match_editorials&amp;d2=srm338 (CAKE)

• https://www.spoj.com/problems/CF36D/ (5) //Pattern watching (care for 1)

• https://codeforces.com/contest/15/problem/C (4) //VERY NICE [XOR: A,1,A+1,0..repeat]

• https://codeforces.com/contest/39/problem/E (4) //Slightly [DP][MATH][ROUNDING]

• https://codeforces.com/contest/63/problem/E (5) //[NICE][BITMASK-DP]

• 12910 — Snakes and Ladders [UVA]

• UVA 10828

• https://codeforces.com/gym/100923/problem/C

• 4963 [LA]

• UVA 12849

• Gym 100962A [2015-2016 Petrozavodsk Winter Training Camp, Moscow SU Trinity Contest][NICE]

• UVA 10109 [NICE][HARD-WORK]

• https://www.spoj.com/problems/ADAPICK/

• https://www.spoj.com/problems/ADAKOHL/

• https://codeforces.com/gym/101808/problem/E (5)

• https://codeforces.com/gym/101808/problem/A (2)

• https://codeforces.com/gym/101666 A

• https://codeforces.com/gym/101726/problem/J (5) //[NICE][INTERSECTION][DS]

• https://codeforces.com/gym/101650 F //Polygons + circles

• https://codeforces.com/gym/101650 H //A few if's

• https://codeforces.com/contest/908/problem/C (3)

• https://codeforces.com/contest/140/problem/A (3) //Circles around bigger circle

• https://codeforces.com/contest/136/problem/D (4) //+Brute-Force

• https://codeforces.com/contest/127/problem/A (1) //Points distance

• https://codeforces.com/gym/101597/problem/B (3) //Simply brute-force just the closest to points

• https://codeforces.com/contest/70/problem/D (5) //Dynamic Convex Hull

• https://icpc.kattis.com/problems/airport //Proposed by tautsjasiunsas

• https://www.hackerrank.com/contests/world-codesprint-7/challenges/elastic-rope/problem

• https://devskill.com/CodingProblems/ViewProblem/20 [EASY]

• UVA 10321 //Polygon intersection

• UVA 11265 //Polygon point +/-

• UVA 13112 //Polygon

• 10907 UVA [Area of polygon from a point]

• 3378 — Swamp Things [LA] — Maximum points on line

• UVA 11768 //Discrete points

• 2542 [LA] //Arc size [formula]

• UVA 1571 //As below [easier]

• https://www.codechef.com/problems/ALLPOLY //[NICE] Point seeing polygon

• https://www.spoj.com/problems/IITKWPCL/ //Point distance

• UVA 11281 //circle~triangle

• UVA 12921 //circle reconstruction

• UVA 190 //circle from 3 points

• UVA 12240 //pts>circle

• UVA 438 //circle pt

• LightOJ 1018 //Minimum # of lines through all pts [VERY NICE]

• UVA 11008 //Similar as above

• UVA 12830 //Biggest rectangle without points inside

• UVA 11012 //Most distant points

• UVA 1683 //Closest points

• UVA 12389 //3D MH Closest Points

• https://www.spoj.com/problems/AMR12C/ //Pt closest to all other points

• https://www.spoj.com/problems/CLOPPAIR/ //Closest pair of points

• UVA 10678 //Circles intersection

• https://codeforces.com/problemset/problem/600/D //Circles intersection

• LightOJ 1118 //Circles intersection

• https://www.spoj.com/problems/CERC07C/en/ //Bounding circle

• UVA-10005 //Bounding circle

• 2407 [LA] //Bounding Sphere

• LightOJ 1120 //Rectangle's Union

• LightOJ 1130 //Circle x Rectangle intersection

• UVA 11177 //Circle x Convex Polygon

• https://codeforces.com/problemset/problem/610/D //Lines intersections (axes parallel)

• 6263 [LA] //Pt in areas

• LightOJ 1058 //# parallelograma

• UVA 12931 //Common area of polygons

• UVA 10301 //Intersecting circles

• UVA 453 //Circles intersection

• https://codeforces.com/problemset/problem/681/E //Circles intersection

• UVA 920 //Lines intersecion (etc..)

• UVA 12556

• https://codeforces.com/problemset/problem/793/C //Intersection ans similar

• UVA 11343 //Intersection of segments

• UVA 866 //Intersection of segments

• Gym 100190I [2011 ACM-ICPC East Central North America (ECNA 2011)] //Segment intersection

• https://codeforces.com/gym/100917/problem/K

• UVA 11686 //Segment intersection

• LightOJ 1388

• UVA 833 //Segment intersection

• LightOJ 1196 //Points sides

• UVA 10167 //Points sides

• UVA 12818 //Arc & Point distance

• https://www.spoj.com/problems/SICRANO/ //Point-line distance

• https://codeforces.com/problemset/problem/614/C //Point-line distance

• UVA 13117 //Point-line distance

• UVA 12483 //Point-line distance

• UVA 12173 //Point-line distance

• UVA 10075 //Point distance on sphere

• https://www.hackerrank.com/contests/booking-hackathon/challenges/nearby-attractions/problem //Pt sphr

• UVA 535 //Point distance on sphere

• UVA 10897 //Sphere tavelling

• UVA 11817 //Sphere travelling

• UVA 10316 //Sphere travelling

• UVA 1469 //Fractions distance 3D

• 11930

• 12173 UVA 3

• 12194 UVA 4

• 11894 UVA 3

• 11769 UVA 7

• 11665 UVA 5

• 11509 UVA 4

• 11355 UVA 5

• 11265 UVA 6 //Nice one | polygon — cut/pt-check/area

• 11123 UVA 4 //Counting trapezoids

• 11177 UVA 6 //BS+Polygon/Circle intersection

• 11186 UVA 3

• 11008 UVA 5 //with DP → #intersected triangles

• 11012 UVA 5 //Nejvzdálenější body (Manhatton 3D)

• 11072 UVA 4 //Points v poly gonu

• https://codeforces.com/problemset/problem/682/E 6 (biggest triangle)

• https://codeforces.com/contest/672/problem/C 4 //easy — just think it up

• https://codeforces.com/contest/667/problem/A 2 //vzorecky

• https://codeforces.com/contest/793/problem/C 5 //EASY but beware of epsilons (NICE)

• https://codeforces.com/contest/794/problem/B 2 //Can be done with BS

• https://codeforces.com/contest/814/problem/D 5 //+DP on trees (NICE — but low geom.)

• 10750 UVA 3 //Closest points — try all pairs

• https://codeforces.com/contest/820/problem/B 3 //Polygon angle find!

• 13213 UVA 5 //VERY NICE — Voronoi diagram (low constraints so not actually needed)

• 13215 UVA 3 //EASY — Sum areas and find side lengths

• https://www.spoj.com/problems/IITKWPCC/ (5) //VERY VERY NICE — Nqrt(N)log(N)

• https://www.spoj.com/problems/NNS/ (5) Closest points query [fake geometry] {__128}[NICE]

• https://codeforces.com/contest/849/problem/B (3) //X-Product — side

• https://www.spoj.com/problems/AMR12C/ (5) //Point closest to all other points (with speed)

• https://www.spoj.com/problems/SICRANO/ (3) //Line-Point distance

• https://www.spoj.com/problems/VCIRCLES/ (5) //Heavy geometrical ****

• https://www.spoj.com/problems/CIRU/ (5) //Same as above [yet bigger constraints]

• https://www.spoj.com/problems/THREETW1/ (4) //Fermat point search

• https://www.spoj.com/problems/CLOPPAIR/ (4) //Closest pair of points

• https://www.spoj.com/problems/MAXLN/ (2) //Some basic (4*r^2+.25)

• https://www.spoj.com/problems/KOLICA/ (4) //VERY NICE [nasty iff party]

• https://codeforces.com/contest/598/problem/C (4) //NICE ~ Precision! [ld]

• https://codeforces.com/contest/18/problem/A (2) //EASY&FINE: Pythagoreas

• https://codeforces.com/contest/40/problem/A (2) //[EASY][DISTANCE]

• https://codeforces.com/gym/101666 H //[VERY NICE][GEOMETRY][DSU][EULER][PLANAR]

• 2827 [LA] //3Coloring

• 2243 [LA] //3Coloring

• 5603 [LA] //Coloring

• UVA 1658 //Shortest paths

• UVA 12821 //Shortest paths

• https://codeforces.com/contest/27/problem/D (5)

• 11387 (UVA) 4

• https://www.spoj.com/problems/VFRIEND2/ (5) //Graph possible check

• https://codeforces.com/contest/859/problem/E (4) //VERY NICE (2 cases: CYCLE [x2] / TREE [x(Size+1)]

• https://codeforces.com/contest/847/problem/C (2) //Forest making Easy&Nice

• https://codeforces.com/contest/863/problem/C (3) //Cycle in states

• https://codeforces.com/gym/101666 (4) //[NICE][QUEUE][DFS][EVENTS]

• https://codeforces.com/gym/101806/problem/T (5) //[NICE][SEGMENT TREE][SORTING]

• https://codeforces.com/contest/916/problem/B (3) //[BITS] FIRST & LAST

• https://codeforces.com/contest/913/problem/C (3) //+[DP]

• https://codeforces.com/contest/146/problem/D (4) //[NICE][CONSTRUCTION]

• https://codeforces.com/contest/146/problem/C (3) //[EASY][NICE][TWO-CASES]

• https://codeforces.com/contest/139/problem/D (4) //Muchas cases

• 7887 — Back to the Future (4) //[NICE][2*HEAP]

• https://codeforces.com/contest/910/problem/A (2) //DP works too

• https://codeforces.com/contest/125/problem/D (4) //Limited possibilities

• https://codeforces.com/contest/902/problem/A (2) //Just keep last

• https://codeforces.com/contest/898/problem/D (4) //[NICE][FENWICK/OR/PREFIX]

• https://codeforces.com/contest/118/problem/C (4) //[NICE] — Try each digit (iterate in waves)

• 7706 — Pokemons (2) //Sweep and keep maximum

• https://codeforces.com/contest/893/problem/D (4) //[NICE][SWEEP][MAXIMUM] — pay max when have to

• https://codeforces.com/contest/892/problem/B (2) //Sweep from back

• https://codeforces.com/contest/102/problem/C (3) //sort by frequency

• https://devskill.com/CodingProblems/ViewProblem/419 (2) //Sweep from back

• https://codeforces.com/contest/890/problem/C (3) //frequence

• https://codeforces.com/contest/890/problem/B (2) //[EASY][REVERSE]

• https://codeforces.com/contest/888/problem/B (2) //Equalize U/D and L/R

• https://codeforces.com/gym/101597/problem/J (4) //[NICE][SWEEP]

• https://codeforces.com/contest/76/problem/B (4) //[NICE][MATCHING-LIKE][2PTRS]

• https://codeforces.com/contest/73/problem/B (4) //[IMPLEMENTATION][SORTING]

• https://codeforces.com/contest/883/problem/K (4) //Nice — Two sweeps

• https://codeforces.com/contest/49/problem/D (3) //NICE — 1010101 OR 0101010 [haming]

• https://codeforces.com/contest/58/problem/C (4) //NICE — group trees by slopes

• https://codeforces.com/contest/729/problem/D 3

• https://codeforces.com/contest/729/problem/E 4

• https://codeforces.com/contest/725/problem/D 4

• https://codeforces.com/contest/725/problem/F 9

• https://codeforces.com/contest/732/problem/E 5

• https://codeforces.com/contest/727/problem/F 6

• https://codeforces.com/contest/724/problem/D 5

• https://codeforces.com/contest/723/problem/C 4

• https://codeforces.com/contest/719/problem/B 2

• https://codeforces.com/contest/712/problem/C 3

• 13152 UVA (4)

• https://codeforces.com/contest/746/problem/E 5

• https://codeforces.com/contest/746/problem/D 3

• https://codeforces.com/contest/749/problem/C 3

• 11737 UVA (3)

• 11786 UVA (4)

• 11630 UVA (5)

• 11563 UVA (4)

• 11491 UVA (4)

• 11330 UVA (3)

• 11089 UVA (2)

• https://codeforces.com/contest/884/problem/D (4) //PQ or Sort

• https://www.spoj.com/problems/SQRMINSUM/ 3 //solve-able in O(N+M)-arrayqueue

• https://www.spoj.com/problems/MSCHED/ 3 //sweep from back

• https://www.spoj.com/status/ns=18780683 4 //all perm + A<B<C works

• https://www.spoj.com/problems/NINJA7/ (3) //sort by diff

• https://www.spoj.com/problems/NINJA2/ (4) //try all possib. (26)

• https://codeforces.com/contest/767/problem/E (6)

• https://codeforces.com/contest/637/problem/B (3) //NICE pro prvaky

• https://codeforces.com/contest/777/problem/B (3) // -||-

• https://codeforces.com/contest/777/problem/D (3) //just go from end

• https://codeforces.com/contest/779/problem/C (3) //NICE pro prváky

• https://www.spoj.com/problems/SPCU/ (2) //Easy — zamysleni (max int = index)

• https://www.spoj.com/problems/LOPOV/ (4) //sort + queue (or just queue) NICE

• https://codeforces.com/contest/792/problem/E (5) //T%S<=T/S + check proper

• https://codeforces.com/contest/807/problem/E (5) //NICE — put asice P2 / rest — greedy from small

• https://codeforces.com/contest/799/problem/E (5) //Many queues — but NICE

• https://codeforces.com/contest/808/problem/C (3) //EASY

• https://codeforces.com/contest/802/problem/B (4) //Priority by "next"

• 10850 UVA (4) //Queue a brute-force

• https://codeforces.com/contest/813/problem/A (1) //Zahrivacka pro prvaky

• 10716 UVA (4) //NICE — always find closest pair

• https://codeforces.com/contest/816/problem/C (3) //NICE — greater<lesser side

• https://codeforces.com/contest/820/problem/D (5) //VERY NICE — O(N) -~- 5 events per number

• https://codeforces.com/contest/818/problem/B (2) //Zahrivacka pro prvaky

• https://codeforces.com/contest/822/problem/C (4) //Almost classical Sort+Queue

• https://codeforces.com/contest/825/problem/C (2) //Nice & Easy

• https://codeforces.com/contest/825/problem/D (3) //Update by modulo

• https://codeforces.com/contest/835/problem/B (2) // Zahhrivacka pro prvaky

• https://codeforces.com/contest/839/problem/B (3) //Nasty iffs — yet nice excersize

• https://www.spoj.com/problems/PCPC12I/ (4) //Swipe MINIMUM from left/right [10^6-A[i] trick]

• https://www.spoj.com/problems/AMR12I/ (3) //NICE a) MAX_SEG>=K b) (SEG_SIZE-1)/K+1

• https://www.spoj.com/problems/BUSYMAN/ (2) //NICE&EASY — Sort + keep minimum

• https://codeforces.com/contest/861/problem/C (3) //2+ but not same

• https://www.spoj.com/problems/WORKB/ (3) //Simple "min" formula for each neighbor

• https://codeforces.com/contest/864/problem/D (4) //VERY NICE — Frequency + unused

• https://www.spoj.com/problems/ROADTRIP/ (4) //VERY NICE — Keeping last lesser

• https://codeforces.com/contest/597/problem/B (3) //NICE [Classical]

• https://www.spoj.com/problems/SHLIGHTS/ (4)

• https://www.spoj.com/problems/MLK/ (3) //VERY NICE — Sum all prefix sums

• https://codeforces.com/contest/867/problem/C (4) //NICE [IMPLE][2POINTERS][MID+EPS]

• https://codeforces.com/contest/867/problem/E (5) //NICE [EASY-IMPLE][HARD-CONS]

• https://codeforces.com/contest/18/problem/D (4) //+Big Integer

• https://codeforces.com/contest/276/problem/D (4) //NICE — Find first mismatch bit (then 111...111)

• https://codeforces.com/contest/3/problem/B (4) //Divide 1/2 [sort][2pointers]

• https://codeforces.com/contest/3/problem/D (4) //?==) ..if open < 0: set max A-B to (

• https://codeforces.com/contest/26/problem/B (4) // +1 ( | -1 ): -1, erase .. erase sum in the end

• https://codeforces.com/contest/33/problem/A (2) //EASY [long-statement]

• https://codeforces.com/contest/44/problem/E (2) //Try mins then try maxs

• https://codeforces.com/contest/45/problem/D (3) //Priority-queue+'sort'

• https://www.spoj.com/problems/ADACLEAN/

• https://codeforces.com/gym/101808/problem/B (5) //[NICE][NUMBERS]

• https://codeforces.com/gym/101741/problem/K (5) //[NICE][SQRT][PATTERN MATCHING]

• 7979 — Red Rover (3) //[NICE] //Many other ways to solve

• https://codeforces.com/contest/898/problem/F (5) //[VERY NICE]//Hash by 10

• https://codeforces.com/contest/114/problem/D (4) //[NICE] //N^2Log(N) might/might-not be OK

• https://www.urionlinejudge.com.br/judge/en/problems/view/1503 (7) //[NICE][BS][OPTI]

• Gym 101466E [2017 ACM-ICPC, Universidad Nacional de Colombia Programming Contest][NICE]

• 12012 UVA 4

• https://codeforces.com/contest/727/problem/E 7

• https://codeforces.com/contest/718/problem/D 8

• 11855 UVA 4

• https://codeforces.com/contest/752/problem/D 5

• https://codeforces.com/contest/825/problem/F 5 //String + Periods

• https://codeforces.com/contest/835/problem/D 4 //Palindromes

• https://www.spoj.com/problems/CF25E/ (5) //VERY NICE [IMPLE>CONCEPT]

• https://codeforces.com/contest/7/problem/D (4) //Palindromes

• https://codeforces.com/contest/19/problem/C (4) //[NICE]: Not a string

• https://www.spoj.com/problems/GARDENHU/en/

• 2453 — Wall [LA]

• UVA 13213

• UVA 11096

• Gym 100792G [2015-2016 ACM-ICPC, NEERC, Moscow Subregional Contest]

• https://www.codechef.com/problems/KTHCON

• https://codeforces.com/problemset/problem/605/C

• UVA 218

• UVA 11072

• 11168 UVA

• UVA 12307

• Gym 100963I [2007-2008 Summer Petrozavodsk Camp, Japanese Contest, 2007-08-29]

• UVA 11243

• UVA 10256

• 109 SCUD Busters

• UVA 13024 [NICE]

• UVA 10002

• Gym 100886H [2015-2016 Petrozavodsk Winter Training Camp, Saratov SU Contest]

• UVA 1139

• UVA 681

• UVA 811

• https://www.codechef.com/problems/MGCHGEOM

• UVA 11769 //3D

• https://www.spoj.com/problems/ADACHESS/

• https://www.spoj.com/problems/ADACHES2/

• https://www.spoj.com/problems/ADAGAME5/

• https://www.spoj.com/problems/ADAXMAS/

• https://codeforces.com/contest/131/problem/E (4) //[NICE][STL][SORTING][QUEEN]

• https://codeforces.com/contest/42/problem/B (4) //NICE — Checkmate check

• UVA 10748 //bfs

• LightOJ 1143

• https://www.hackerearth.com/practice/algorithms/greedy/basics-of-greedy-algorithms/practice-problems/algorithm/harry-and-ron-play-a-game-of-chess/

• UVA 10196

• https://www.spoj.com/problems/KNMOVE/

• UVA 11352

• https://www.spoj.com/problems/NAKANJ/ //BFS

• LightOJ 1010

• LightOJ 1171 //MM

• 2883 LA

• UVA 439

• https://www.spoj.com/problems/TRKNIGHT/ //??

• 2308 LA

• https://www.spoj.com/problems/CCHESS/ //Dijkstra

• https://codeforces.com/problemset/problem/630/H //[ROOKS][BIG][COMBINATORICS]

• LightOJ 1005 //As above (but with real rooks)

• LightOJ 1061 //Placing queens

• UVA 11085

• UVA 10094 //Queen placing [NICE][PATTERN]

• https://devskill.com/CodingProblems/ViewProblem/383

• 11852 UVA (6)

• https://www.spoj.com/problems/KLUG1/ (2) //Jumps of horse

• https://www.spoj.com/problems/CODESPTD/ (5) //VERY NICE — DP [Queens]

• https://codeforces.com/contest/3/problem/A (2) //Imple — Shortest path for king

• https://codeforces.com/contest/38/problem/B (2) //NICE — Simple possition checking

• https://codeforces.com/gym/101889/my H

• https://codeforces.com/contest/934/problem/A (2)

• https://codeforces.com/contest/922/problem/A (2) //Iff-party

• https://codeforces.com/contest/914/problem/A (1)

• https://codeforces.com/contest/916/problem/A (2) //Time

• https://codeforces.com/contest/915/problem/B (2) //Formula / Iff

• https://codeforces.com/contest/915/problem/A (1)

• https://codeforces.com/contest/913/problem/A (1)

• https://codeforces.com/contest/912/problem/A (2) //Easy [corner-cases]

• https://codeforces.com/contest/146/problem/A (1)

• https://www.spoj.com/problems/ESYR/ (1) //Bad one :/

• https://codeforces.com/contest/908/problem/A (1)

• https://codeforces.com/contest/147/problem/A (2) //Parsing

• https://codeforces.com/contest/139/problem/A (1)

• https://codeforces.com/contest/137/problem/A (1)

• 7886 — Assigning Teams (2) //[EASY][SORTING]

• https://codeforces.com/contest/133/problem/A (1)

• https://codeforces.com/contest/134/problem/A (1)

• https://codeforces.com/contest/131/problem/A (1)

• https://codeforces.com/contest/127/problem/B (1) [EASY]

• https://codeforces.com/contest/899/problem/B (2) //Dates

• https://codeforces.com/contest/898/problem/C (3) //No thinking — just implementation

• 6157 How do spiders walk on water? (4) //boring problem

• https://codeforces.com/contest/900/problem/A (1)

• 7613 Relative atomic mass (1)

• https://codeforces.com/contest/122/problem/A (1) //Find all lucky

• https://codeforces.com/contest/120/problem/B (1) //Iteration

• https://codeforces.com/contest/120/problem/A (1) //Iff/Logic

• https://codeforces.com/contest/118/problem/B (2) //[PRINTING]

• https://codeforces.com/contest/108/problem/A (1) //[EASY][PRINT][TIME]

• https://codeforces.com/contest/106/problem/A (1) //Iff-party

• https://codeforces.com/contest/890/problem/A (1) //if or perm

• https://codeforces.com/contest/90/problem/B (2) //No idea — just cycles

• https://codeforces.com/contest/75/problem/A (1) //conversion

• https://codeforces.com/contest/884/problem/B (1) //Simple sum +N-1

• https://codeforces.com/contest/48/problem/A (1) //Very easy [fe. perm]

• https://codeforces.com/contest/51/my (2) //Lex-lowest-string (|s|=4)

• https://codeforces.com/contest/54/problem/A (2) //Single sweep

• https://codeforces.com/contest/719/problem/C 3

• https://codeforces.com/contest/747/problem/E 4

• https://codeforces.com/contest/754/problem/C 5

• 11482 UVA (4)

• 11291 UVA (3)

• 11070 UVA (5) //evaluation of expression

• 11074 UVA (2)

• https://codeforces.com/contest/678/problem/B 2 //calendar days

• https://codeforces.com/contest/643/problem/A 3 //easy — just simulate

• https://codeforces.com/contest/770/problem/D 5 //easy — but pain — draw

• https://codeforces.com/contest/789/problem/B 3 //simulate (mby twice)

• 13171 UVA (1)

• 10800 UVA (3)

• https://codeforces.com/contest/828/problem/B 2 //EASY & NICE — just analysis

• https://codeforces.com/contest/825/problem/B 2 //EASY & NICE — Piskvorky — pro prvaky

• https://codeforces.com/contest/837/problem/B 2 //Just implementation

• https://codeforces.com/contest/837/problem/C 2 //Some nasty iffs

• https://codeforces.com/contest/845/problem/B 2 //Easy pro prvaky

• https://codeforces.com/contest/845/problem/D 3 //Iffs — folow the rules

• https://www.spoj.com/problems/UNIHW/ 4 //NICE (but many iffs)

• https://codeforces.com/contest/5/problem/A (2) //Parsing

• https://codeforces.com/contest/5/problem/B (3) //Output formating

• https://codeforces.com/contest/6/problem/B (2) //Simply check by adjancecy vector + set

• https://codeforces.com/contest/7/problem/A (1) //Oneinteresting if

• https://codeforces.com/contest/8/problem/B (2) //Sample vectors + set/or/array

• https://codeforces.com/contest/12/problem/A (1) //Find mirror by middle

• https://codeforces.com/contest/16/problem/A (1) //Easy check of chars

• https://codeforces.com/contest/21/problem/A (2) //Easy but nasty iff imple

• https://codeforces.com/contest/31/problem/B (2) //Boring imple

• https://codeforces.com/contest/34/problem/C (3) //Easy string parsing

• https://codeforces.com/contest/41/problem/C (2) //String parsing

• https://www.spoj.com/problems/KPRIMESB/ (4)

• https://www.spoj.com/problems/IITKWPCH/ (4) //NICE — on bits

• https://www.spoj.com/problems/SUBSET/ (5) //VERY NICE — 3^10 (^2 but not exactly) (+ sorting)

• https://www.hackerearth.com/practice/algorithms/dynamic-programming/bit-masking/practice-problems/algorithm/special-pairs-7/description/ (4) //NICE [Brute-force]

• https://codeforces.com/contest/897/problem/D (4) //NICE! Back/Front

• https://codeforces.com/contest/727/problem/C (2)

• https://codeforces.com/contest/810/problem/D (4) //BS * 3 (same)

• https://codeforces.com/contest/811/problem/D (4) //BFS — easy .. some ifs

• https://codeforces.com/contest/835/problem/E (4) //NICE! Bitsets + Detect + XOR

• https://codeforces.com/contest/844/problem/D (5) //NICE! Randomized algo

• https://codeforces.com/contest/862/problem/D (4) //NICE! Find first + Binary Search

• https://codeforces.com/contest/872/problem/D (4) //NICE! [no clue why it passed]

• UVA 12489 //Tree

• https://www.hackerrank.com/contests/hourrank-16/challenges/jenny-subtrees/problem

• https://www.spoj.com/problems/DSUBTREE/ (5) //Isomorphism on trees (try all subsets)

• https://www.spoj.com/problems/TREEISO/ (4) //Simple isomorphism of trees

• UVA 151

• UVA 1394

• UVA 440

• 3803 [LA]

• https://www.urionlinejudge.com.br/judge/en/problems/view/1030

• UVA 12912

• UVA 13114

• 11351 UVA (2)

• https://www.spoj.com/problems/CLSLDR/ (4) //Muchas queries — go DP

• https://www.spoj.com/problems/WTK/ (Easy) Suggested by ayushgupta1997

• https://www.spoj.com/problems/DANGER/ (Easy) Suggested by ayushgupta1997

• https://www.spoj.com/problems/POCRI/ (Medium) Suggested by ayushgupta1997

• https://www.spoj.com/problems/NG0FRCTN/ (Medium) Suggested by ayushgupta1997

• https://www.spoj.com/problems/ADAPET/

• UVA 12604

• UVA 12467

• UVA 11019

• https://www.spoj.com/problems/NAJPF/ (4) //classical kmp — all patterns

• https://codeforces.com/contest/808/problem/G (6) //with DP -harder

• https://www.spoj.com/problems/ADAAPPLE/ [HLD][LCT works too]

• https://www.spoj.com/problems/ADAVISIT/ [HLD]

• https://www.spoj.com/problems/ADALICI/ [KTH Ancestor — FAST!]

• https://www.spoj.com/problems/ADAORANG/

• https://codeforces.com/gym/101808/problem/K (5) //[NICE][IMPLEMENTATION][CYCLE]

• https://www.spoj.com/problems/LCA/ //Easiest one — low constraints [practice]

• https://www.spoj.com/problems/LCASQ/

• https://codeforces.com/contest/916/problem/E (6) //[VERY NICE][SEG-TREE]//REROOT

• https://codeforces.com/contest/911/problem/F (5) //[VERY NICE][LONGEST PATH]

• https://devskill.com/CodingProblems/ViewProblem/141

• UVA 12655

• https://www.codechef.com/problems/PSHTTR

• LightOJ 1162

• Gym 100685G [2012-2013 ACM-ICPC, NEERC, Moscow Subregional Contest]

• UVA 12533

• https://www.codechef.com/problems/CLOSEFAR //But kinda more comples [ST]

• https://codeforces.com/contest/733/problem/F 7

• 11354 UVA (4)

• https://www.spoj.com/problems/POLICEMEN/ (3) //simple + small graph

• https://www.spoj.com/problems/QTREE2/ (5) //very easy if bin. understrood

• https://codeforces.com/contest/828/problem/F 7 // Differently MST / Outside

• https://codeforces.com/contest/832/problem/D (5) //Classical + Depth /OR/ HLD +ST

• https://www.spoj.com/problems/DRTREE/ (5) //NICE [finding ancestor + depths]

• https://codeforces.com/problemset/problem/838/B (6) //VERY NICE [HLD + ET + ST]

• https://www.spoj.com/problems/NTICKETS/ (4) //Maximum on path

• https://www.spoj.com/problems/GRASSPLA/ (5) //HLD

• https://codeforces.com/contest/855/problem/D (4) //VERY VERY BAD STATEMENT (not so bad problem)

• https://codeforces.com/gym/101630 {L}(6) //[NICE][HLD or DSU][XOR] //Parenthessis

• https://www.spoj.com/problems/ADASEED/ [HUNT]

• https://www.spoj.com/problems/MC/

• UVA 10192

• UVA 531

• LightOJ 1110

• UVA 12747 //Perm

• https://www.spoj.com/problems/XMEN/ //Perm

• UVA 10405

• UVA 12511 //Increasing

• UVA 10635 //Increasing

• 10949 UVA (6) — Hunt or Bit

• https://www.spoj.com/problems/MC/ (3) //Classical

• https://www.spoj.com/problems/LCS0/ (7) //Bit

• https://www.spoj.com/problems/ADAROADS/ [ONLINE][UPDATES][LCT]

• https://www.spoj.com/problems/DYNALCA/en/ //DYNAMIC LCA

• https://codeforces.com/gym/100460/problem/C

• https://codeforces.com/gym/100960/problem/H

• https://www.spoj.com/problems/DYNACON1/

• https://codeforces.com/contest/892/problem/E (7) [VERY NICE]//By prices .. LCT

• UVA 231

• UVA 10131

• 2931 LA

• https://www.spoj.com/problems/NDS/

• UVA 481

• https://www.spoj.com/problems/ELIS/

• UVA 497

• UVA 11790

• https://www.spoj.com/problems/ALTSEQ/ 3 //solvable by FW in Nlog(N)

• https://www.spoj.com/problems/VISIBLEBOX/ (4) //with multiset

• https://www.spoj.com/problems/DOSA/ (5)

• https://www.spoj.com/problems/CODERE3/ 3 //Low bounds LIS/LDS

• https://www.spoj.com/problems/BRDGHRD/ 4 //lis (nondecreasing)

• https://www.spoj.com/problems/GONESORT/ 4 //Permutation-lis + riddle statement

• https://codeforces.com/contest/847/problem/B 4 //Multiple Lis's

• https://codeforces.com/contest/67/problem/D (4) //[NICE][DOUBLE REMAP]

• https://www.spoj.com/problems/ADAPATH/

• https://www.spoj.com/problems/ADACITY/

• https://www.spoj.com/problems/ADAPLNTS/

• https://codeforces.com/gym/101666 E //[NICE][GEOMETRY][BINARY SEARCH][PROBABILITY]

• https://www.spoj.com/problems/MATCHING/ //Raw (no sauce)

• https://codeforces.com/contest/116/problem/B (3) //Low cons. Can be done without algo

• 6234 — Tile Cut (LA)

• 10080 — Gopher II (UVA) //Easy — sympathic

• 11419 — SAM I AM (UVA) //Grid-Matching

• https://codeforces.com/gym/101485 (Elementary Math — E) //Very nice principal [not that hard]

• 3673 — Black-White Grid (UVA) //Grid

• 12927 — Points Cover (UVA)

• 6851 — The Programmers (LA)

• 6887 — Book Club //NICE

• 6571 — It Can Be Arranged

• 12530 — Game of Tiles

• https://codeforces.com/gym/100820 (Airport — A) //Nice one

• https://codeforces.com/gym/100753 (Bounty Hunterr II — B) //VERY NICE — I refered multiple times to this principal

• https://codeforces.com/gym/101408 (Cat vs Dog — C)

• 1171 — Knights in Chessboard (II) (LOJ) //Classical chess

• 12644 — Vocabulary

• https://codeforces.com/gym/101047/problem/H

• https://codeforces.com/problemset/problem/659/E

• 12972 — Cuban Challenge (UVA)

• 1201 — Taxi Cab Scheme (UVA)

• 12963 — Astragalus Nitidiflorus

• 6525 — Attacking rooks (LA)

• 3415 — Guardian of Decency (LA)

• 12159 — Gun Fight (UVA)

• https://www.codechef.com/problems/CHEFYODA //Imho matching is not the crucial part here

• 12831 — Bob the Builder

• https://codeforces.com/problemset/problem/831/D

• 11262 — Weird Fence

• 12549 — Sentry Robots

• 11138 — Nuts and Bolts

• https://codeforces.com/contest/727/problem/D 4

• 11985 UVA (5)

• https://www.spoj.com/problems/AMR12A/ (5) //VERY NICE goophers + bonus

• https://www.spoj.com/problems/NITT4/ (4) //VERY NICE [Chessboard matching]

• https://www.spoj.com/problems/SCPC11H/ (4)//NICE — Match those which fits inside

• 12045 UVA (4)

• https://www.spoj.com/problems/ADAMONEY/

• 13284 Macarons (4) //[NICE][BITMASK][DP] Classical

• https://codeforces.com/contest/147/problem/B (5) //[NICE][BS][GRAPHS]

• https://codeforces.com/contest/107/problem/D (5) //[NICE][DP]

• UVA 12653

• LightOJ 1131

• UVA — 12470

• https://codeforces.com/problemset/problem/696/D

• https://www.hackerrank.com/contests/mathemagic-bits/challenges/gp-on-fibonacci-matrix [accesable?]

• https://www.hackerrank.com/contests/mathemagic-bits/challenges/degree-diameter-on-trees [accesable?]

• LightOJ 1052

• https://www.codechef.com/problems/KBIGNUMB

• LightOJ 1160

• LightOJ 1096

• UVA 11486

• https://codeforces.com/problemset/problem/718/C

• LightOJ 1070

• LightOJ 1132

• https://codeforces.com/problemset/problem/621/E

• Project Euler #114: Counting block combinations I

• https://codeforces.com/problemset/problem/821/E

• UVA 12593

• https://www.codechef.com/AUG16/problems/SHAIKHGN //Not exactly but similar principle

• 11551 UVA (4)

• 11486 UVA (5)

• 10743 UVA (5) //A001169 [easy multi / hard to come with recurence]

• https://codeforces.com/contest/821/problem/E (6) //Not trivial to come-up with matrix

• https://www.spoj.com/problems/DCEPCA06/ (4) //NICE — 10x10 matrix

• https://www.spoj.com/problems/GSWORDS/ (3) //NICE&EASY — 3-states "OO,OX,XO"

• https://www.spoj.com/problems/TETRAHRD/ (4) //Easy + Sum

• https://www.spoj.com/problems/NACCI/ (4) //Classical (N-Bonacci)

• https://www.spoj.com/problems/JZPCIR/ (5) //VERY NICE: A137726

• https://www.spoj.com/problems/ADAGROW/

• https://www.spoj.com/problems/ADAFEAR/

• 13288 — Cordon Bleu (6) //[NICE][MATCHING]

• https://codeforces.com/gym/100800 (Aqueduct Construction — A)

• 10806 — Dijkstra, Dijkstra.

• 12944 — Earthquake Disaster

• 12891 — Risk of Trading

• https://www.codechef.com/problems/HOGON

• https://codeforces.com/contest/863/problem/F (5) //VERY NICE

• 11613 UVA (6)

• https://codeforces.com/contest/802/problem/C (8) //Nice but hard to see + negative

• https://codeforces.com/contest/802/problem/N (5) //Easy but faster MCMF needed

• https://codeforces.com/contest/818/problem/G (6) //NICE + MUCH Faster MCMF

• https://www.spoj.com/problems/BNMT/ (7) //VERY NICE (some optimalisations needed + weird data set)

• https://codeforces.com/contest/884/problem/F (6) //Alphabetical buckets

• https://codeforces.com/contest/713/problem/C 7

• https://www.spoj.com/problems/RMID2/ 4

• https://www.spoj.com/problems/RMID/ 3 (as above just not so dynamic)

• https://www.spoj.com/problems/EC_ESTA/ 4 //classical dynamic median

• https://www.spoj.com/problems/DCEPCA09/ (6) //VERY NICE [MO +++ MEDIAN, MEAN, FREQ]

• https://codeforces.com/contest/912/problem/E (5) //[VERY NICE][BS][2P][PRIMES]

• https://codeforces.com/contest/888/problem/E (4) //NICE[EASY]

• https://codeforces.com/contest/51/problem/E (6) //NICE[GRAPH][Cycles of length 5]

• https://devskill.com/CodingProblems/ViewProblem/245

• https://devskill.com/CodingProblems/ViewProblem/256

• 11851 UVA (5)

• 11465 UVA (5)

• 13207 UVA (4) //Straight-forward MIM

• https://www.spoj.com/problems/COLOR_CC/ (4) //VERY NICE — div by partity (take lesser) → 8^6

• https://www.spoj.com/problems/ADAUNIQ/ [Updates]

• https://www.spoj.com/problems/ADANUM/

• https://www.spoj.com/problems/ADAPEAR/

• https://www.spoj.com/problems/ADAPHONE/

• https://www.spoj.com/problems/ADAFTBLL/ [Tree][Updates]

• https://www.spoj.com/problems/FREQUENT/

• https://codeforces.com/contest/86/problem/D (4) //[NICE][CLASSICAL]

• https://codeforces.com/contest/877/problem/F (6) //[NICE][NORMALIZE]

• https://codeforces.com/problemset/problem/687/D

• https://codeforces.com/problemset/problem/617/E

• https://www.spoj.com/problems/DCEPCA09/

• https://www.spoj.com/problems/COT2/

• https://www.codechef.com/problems/DISTNUM3 //Tree + Update

• https://toph.ws/p/distinct-dishting //Not sure if still working??

• https://www.codechef.com/problems/CHEFNUMK

• https://www.hackerearth.com/problem/algorithm/harry-gets-into-infy-1/description/

• https://www.spoj.com/problems/COT/ (7) //ON TREE [but very tight TLE]

• https://www.spoj.com/problems/GOT/ (5) //ON TREE

• https://www.spoj.com/problems/CPAIR2/ (4) //MO + Fenwick [VERY NICE]

• https://www.spoj.com/problems/HRSIAM/ (5) //With updates

• https://www.spoj.com/problems/KDOMINO/ (4) //NICE — Frequencies

• 13257 — License Plates UVA //Brute-Force 26^3 queries in O(1)

• https://codeforces.com/contest/92/problem/C (3) //[VERY NICE]

• LightOJ 1157

• https://www.codechef.com/problems/ASTRING

• https://www.spoj.com/problems/MAIN8_E/

• https://codeforces.com/problemset/problem/701/C

• https://www.spoj.com/problems/STRSEQ/ //+DP

• https://codeforces.com/problemset/problem/762/C

• https://codeforces.com/problemset/problem/724/D

• https://www.spoj.com/problems/SUBSN/ //+BS

• https://www.hackerrank.com/contests/world-codesprint-5/challenges/short-palindrome //+DP

• https://www.spoj.com/problems/ADACROW

• https://www.spoj.com/problems/ADAPARTY/

• https://www.spoj.com/problems/ADAPARTI/

• https://codeforces.com/gym/101666 G //[NICE][BURTE FORCE][OBSERVATION][SUBSETS]

• https://codeforces.com/contest/907/problem/E (5) //[VERY NICE][CLIQUE][DP]

• https://codeforces.com/contest/114/problem/B (3) //[CLIQUE][BRUTE-FORCE]

• https://www.spoj.com/problems/JOHNNY/ //Not exact — points

• https://www.spoj.com/problems/TAKIN/ (3) //[KNAPSACK][RECURSION]

• https://codeforces.com/contest/839/problem/E (5) //NICE! Max-Clique

• 7743 — Cliques (Similar to ADAPARTI) (8) //Parametrisation

• 7616 Counting Cliques (4) //[NICE][CLIQUES][ELIMINATING-SETS]

• UVA 10667 //Largest rectangle

• UVA 10074 //Largest rectangle

• UVA 836 //Largest rectangle

• UVA 1330 //Largest rectangle

• 12192 UVA 5

• https://codeforces.com/contest/729/problem/B 2

• https://codeforces.com/contest/710/problem/C 4

• 11871 UVA 6

• 11617 UVA (3)

• 11573 UVA (4)

• 11499 UVA (5)

• 11230 UVA (4)

• https://www.spoj.com/problems/JOCHEF/ (5) //NICE: Lagers rectange 0/1 O(N*M)

• https://www.spoj.com/problems/ADAGCD/ [+STL]

• https://www.spoj.com/problems/ADAHACK/

• https://www.spoj.com/problems/ADADUNG/

• https://www.spoj.com/problems/ADACAROT/

• https://www.spoj.com/problems/ADACON/

• https://www.spoj.com/problems/ADATAXES/

• https://www.spoj.com/problems/ADADIG/

• https://www.spoj.com/problems/ADASETS/

• https://codeforces.com/gym/101808/problem/G (4) //[GCD][IF][LCM]

• https://codeforces.com/gym/101666 L //[GREED][DP] Logarithms

• https://codeforces.com/gym/101666 C //[NICE][GCD]

• 13287 — Shattered Cake (2) //Rectangle

• https://codeforces.com/gym/101650 G //Graphs

• https://codeforces.com/contest/934/problem/D (4) //Polynomials

• 8253 — Boss Battle LA

• https://codeforces.com/contest/919/problem/E (5) //[MODULAR-MATH]

• https://codeforces.com/contest/149/problem/B (3) //Base to 10

• https://codeforces.com/contest/148/problem/B (3) //[SIMULATION](math or bs)

• https://codeforces.com/contest/148/problem/A (2) //[EASY][SIEVE][BRUTE-FOCE][LCM][IE]

• https://www.spoj.com/problems/JGTLE/ (3) //Sum reduction

• https://www.spoj.com/problems/BAPM/ (3) //Simple power / Observe, rare colisions

• https://codeforces.com/contest/911/problem/C (2) //[Observation][Iff (or brute-froce)]

• https://codeforces.com/contest/133/problem/B (2) //Bases + implementation

• https://codeforces.com/contest/129/problem/A (1) //Parity

• https://codeforces.com/contest/124/problem/D (4)

• https://codeforces.com/contest/125/problem/A (1) //mod/div simple — if

• https://codeforces.com/contest/902/problem/D (4) //Polynomials / Fibonacci / Bitset

• https://codeforces.com/contest/899/problem/D (4) //X99999 possibilities

• https://codeforces.com/contest/899/problem/C (3) //[NICE][GREEDY KNAPSACK]

• https://codeforces.com/contest/899/problem/A (1)

• https://codeforces.com/contest/898/problem/A (1)

• https://codeforces.com/gym/101620 {F}(4) //[IFS][INVERSE][CASES]

• https://codeforces.com/contest/900/problem/D (4) //[NICE][DIVISORS][GCD][IE]

• https://codeforces.com/contest/900/problem/B (2) //Cycles or Brute-force + Division

• https://codeforces.com/contest/119/problem/A (2) //[EASY][GCD]

• 8014 — Birthday Pizza Party (4) //[NICE][OVERFLOW][LCM WITH SHIFT]

• 7629 — Powers (3) //One path is factorisation

• 8037 — Military Service (2) //Sample formula

• 8085 — Divisors (4) //[NICE][PRIMES/FACTORISATION/SIEVE]

• 6589 — Captain Obvious and the Rabbit-Man (7) //Sylvester's formula

• 6582 — Magical GCD (4) //[NICE] — Data structures works too

• 8000 — FizzBuzz (1)

• https://devskill.com/CodingProblems/ViewProblem/421 (2) //6 buckets

• https://codeforces.com/contest/93/problem/E (5) //[VERY NICE][DP][RECURSION]

• https://codeforces.com/contest/86/problem/A (3) //[NICE] 50* is best (unless more digits)

• https://codeforces.com/contest/83/problem/D (5) //[VERY NICE][PRIMES][BRUTE-FORE-2]

• https://codeforces.com/contest/82/problem/A (2) //Simulation

• https://codeforces.com/contest/74/problem/C (4) //gcd

• https://codeforces.com/contest/76/problem/E (4) //Divide sumations [BF]

• https://codeforces.com/contest/71/problem/C (3) //[EASY][NICE][BRUTE-FORCE][DIVISORS]

• https://codeforces.com/contest/70/problem/A (2) //3^(N-1)

• https://codeforces.com/contest/43/problem/C (2) //Moduly by 3 {0/2+min(1,2)}

• https://codeforces.com/contest/50/problem/A (1) //[EASY]

• https://codeforces.com/contest/61/problem/C (4) //Base conversion + roman

• UVA 355 //bases conversion

• 2559 [LA] //Base conversion

• https://www.codechef.com/problems/COPRIME3 //Cyka Möbius

• https://www.spoj.com/problems/PSTR/ //Cyka Möbius

• https://codeforces.com/problemset/problem/803/F //Cyka Möbius

• https://devskill.com/CodingProblems/ViewProblem/23

• https://codeforces.com/contest/731/problem/F 4

• 12031 UVA (8)

• https://codeforces.com/contest/722/problem/F (8)

• https://codeforces.com/contest/716/problem/C 4

• https://codeforces.com/contest/711/problem/E (8)

• https://codeforces.com/contest/710/problem/D (6)

• 13154 (UVA) 7

• 13166 (UVA) 5

• 11962 (UVA) 2

• 11718 UVA 3

• 11510 UVA (5)

• 11538 UVA (3) //good one — just math

• 11556 UVA (1)

• https://codeforces.com/contest/757/problem/E (8)

• https://codeforces.com/contest/758/problem/F (7)

• 11481 UVA (4)

• 11237 UVA (4) //Nice — seems like knapsbag but it it not

• 11155 UVA (4) //Almost as previous problem

• 11038 UVA (3) //counting digits on interval

• https://codeforces.com/contest/763/problem/C (7)

• 11087 UVA (4) //Sums of two numbers divisible with <=500 (10^5)

• https://codeforces.com/contest/678/problem/C 2 //LCM

• https://codeforces.com/problemset/problem/665/F (8) //p^3 | p*q

• https://www.spoj.com/problems/LCMSUM/ //Vzorec v knihovničce

• https://www.spoj.com/problems/FRNDZND/ (2) // (size 1 == 1, else 0)

• https://www.spoj.com/problems/EXPOR/ //bit-by-bit (+ formula)

• https://www.spoj.com/problems/FACTDIV/ (5) //dyn-update of ans/factors GOOD

• https://www.spoj.com/problems/PAIRDIV/ (6) //cyka möbius -_-

• https://www.spoj.com/problems/FCDC/ (4) //keep factorized factorial

• https://www.spoj.com/problems/NTHPRIME/ (7) // BS + NumPrime GOOD!!

• https://www.spoj.com/problems/DIVFACT3/ (7) // Sieve 10^8 + sqrt search

• https://www.spoj.com/problems/DIVFACT4/ (8) // Prime count

• https://codeforces.com/contest/776/problem/C (4) //segments div. by number

• https://codeforces.com/contest/776/problem/E (6) //vypsat cisla: f(N)=Phi(N),g(N)=N

• https://www.spoj.com/problems/PHT/ (2) //easy BS (NN+2N) mby math?

• https://www.spoj.com/problems/GCDEX/ (7) //OEIS A006579 — enough [well imp]

• https://www.spoj.com/problems/APS/ (3) //just sieve + generate

• https://www.spoj.com/problems/WPC5I/ (3)//fc: C[a]!=C[b]:F[a]^max(C[a],C[b])

• https://www.spoj.com/problems/SPEC_SET/ N→N/k→N/k/k

• https://www.spoj.com/problems/DCEPC11B/ (5) //Wilson't theorem!

• https://www.spoj.com/problems/FACTMULN/ (5) //each f[i]/c[i] separately

• https://www.spoj.com/problems/SPCM/ (4) //just factorisation + prime check (10^12)

• https://www.spoj.com/problems/TWOGAME/ (5) //gcd == Power of 3 => YES

• https://www.spoj.com/problems/MKEQUAL/ (2) //Chceck if sum is divisible by N

• https://www.spoj.com/problems/TIPTOP/ (3) //sqrt(N)==N? NICE!!

• https://www.spoj.com/problems/PSYCHON/ (4) // fast factorisation

• https://www.spoj.com/problems/ENIGMATH/ (1) // swap and div by gcd

• https://www.spoj.com/problems/SNGPG/ (3) // prime gen + check

• https://codeforces.com/contest/795/problem/A (2) //brute-force

• https://codeforces.com/contest/801/problem/E (6) //NICE! — Clique-DAG + inversion

• https://codeforces.com/contest/798/problem/C (4) //GCD == at the beginning OR 2

• https://codeforces.com/contest/803/problem/C (3) //Only "low" K and just divisors

• 10830 (4) //simple add 2→ sqrt(N) + their mirrors

• https://codeforces.com/contest/817/problem/A (2) //check division + parity

• 13209 UVA (3) //Simple simulation of division (+states rememberance)

• https://codeforces.com/contest/834/problem/C (4) //Has cube-root + both num divisible by cuberoot

• https://codeforces.com/contest/837/problem/E (5) //Factorisation + GCD attributes

• https://www.spoj.com/problems/SUMMATION/ (3) //Number contribution: 2^(N-1)

• https://www.spoj.com/problems/SECTORS/ (4) //Odd len OR sum of odd indices == sum of even

• https://www.spoj.com/problems/IITKWPCM/ (6) //VERY NICE — Gauss's generalisation of Wilsons Theorem

• https://www.spoj.com/problems/UCV2013A/ (4) //N*(N^L-1)/(N-1)

• https://www.spoj.com/problems/KIMO1/ (4) //NICE — Adding/Subing by modulus

• https://www.spoj.com/problems/AFS2/ (4) //Sum of divisort (sqrt(N)) — (+128int)

• https://www.spoj.com/problems/FUNNUMS/ (4) //Permutations (get ith + guess ith)

• https://www.spoj.com/problems/MAY99_3/ (3) //GCD

• https://www.spoj.com/problems/PUCMM334/ (3) //Classical hats problem

• https://www.spoj.com/problems/LCPC11B/ (4) //Factorize + count all subsets

• https://www.spoj.com/problems/THREENUMBERS/ (2) //EASY & NICE [lcm]

• https://www.spoj.com/problems/GAMES/ (2) //EASY&NICE — Go discrete (by 10^k) → 10^k/GCD

• https://www.spoj.com/problems/SUBSHARD/ (4) //dig10^sufix(choose sufix)*^Prefix [VERY NICE]

• https://www.spoj.com/problems/INVDIV/ (6) //Sum of divisors function + factorisation [NICE]

• https://www.spoj.com/problems/JNEXT/ (2) //EASY — Zahřívačka pro prváky

• https://www.spoj.com/problems/TSHOW1/ (3) //NICE — Almost as binary repre with 5/6

• https://codeforces.com/contest/859/problem/B (2) //Easy by iteration

• https://codeforces.com/contest/861/problem/A (2) //5,2 division [EASY]

• https://www.spoj.com/problems/ABA12D/ (4) //NICE — Formula for sum divisors Prod(Sum(fac-powers))

• https://www.spoj.com/problems/MAIN74/ (3) //Fibo's

• https://www.spoj.com/problems/NOSQ/ (3) //Sieve + Digit check

• https://www.spoj.com/problems/SQUAREV1/ (3) //NICE (but dumb code limit)

• https://codeforces.com/contest/597/problem/A (1) //Simple if+2*Divide

• https://www.spoj.com/problems/STREETR/ (3) //Easy [GCD]

• https://www.spoj.com/problems/HPYNOSII/ (3) //<=1000 after first move

• https://www.spoj.com/problems/HPYNOS/ (1) //Same as above — 1 number

• https://www.spoj.com/problems/IITD4/ (3) //Brute-force [sieve-like]

• https://www.spoj.com/problems/GIRLSNBS/ (2) //Some easy formula

• https://www.spoj.com/problems/GUESSTHE/ (2) //NICE [EASY][LCM]

• https://codeforces.com/contest/867/problem/B (2) //NICE [observation][1 2]

• https://www.spoj.com/problems/NDIVPHI/ (4) //NICE — Multiple of lowest primes [BIG-INT]

• https://www.spoj.com/problems/NDIVPHI2/ (5) //NICE — Same as above [bigger constraints]

• https://codeforces.com/contest/6/problem/A (1) //Triangle check (4 pts)

• https://codeforces.com/contest/869/problem/B (1) //Answer is usually 0

• https://codeforces.com/contest/9/problem/C (2) //Bases (2→ 10)

• https://codeforces.com/contest/20/problem/B (2) //Ax^2+Bx+C=0 (find roots)

• https://codeforces.com/contest/27/problem/E (5) //[VERY NICE]: Factorisation+Recursion

• https://codeforces.com/contest/32/problem/C (3) //DSU works too

• https://codeforces.com/contest/872/problem/C (3) //NICE — Compose of 4 (mby one 6 or 9)

• https://codeforces.com/contest/876/problem/B (3) //Group by modulo