In this repository, I have stored solutions to various problems and concepts of **Data Structures and Algorithms** in Python3 in a structured manner.✨
:heavy_check_mark: _**Topics Covered**_:
- [x] [**LeetCode All Problems Solutions**](https://github.com/SamirPaulb/DSAlgo/tree/main/01_LeetCode)
- [x] [**Dynamic Programming**](https://github.com/SamirPaulb/DSAlgo/tree/main/02_Dynamic-Programming)
- [x] [**Sorting Algorithms**](https://github.com/SamirPaulb/DSAlgo/tree/main/03_Sorting-Algorithms)
- [x] [**LinkedList**](https://github.com/SamirPaulb/DSAlgo/tree/main/04_LinkedList)
- [x] [**Object-Oriented Programming**](https://github.com/SamirPaulb/DSAlgo/tree/main/05_Object-Oriented-Programming)
- [x] [**Binary Trees**](https://github.com/SamirPaulb/DSAlgo/tree/main/06_Binary-Trees)
- [x] [**Graph Algorithms**](https://github.com/SamirPaulb/DSAlgo/tree/main/07_Graph)
- [x] [**Heap**](https://github.com/SamirPaulb/DSAlgo/tree/main/08_Heap)
- [x] [**Matrix**](https://github.com/SamirPaulb/DSAlgo/tree/main/09_Matrix)
- [x] [**Trie**](https://github.com/SamirPaulb/DSAlgo/tree/main/10_Trie)
- [x] [**Binary Search**](https://github.com/SamirPaulb/DSAlgo/tree/main/11_Binary-Search)
- [x] [**Backtracking**](https://github.com/SamirPaulb/DSAlgo/tree/main/12_Backtracking)
- [x] [**Stack**](https://github.com/SamirPaulb/DSAlgo/tree/main/13_Stack)
- [x] [**Queue**](https://github.com/SamirPaulb/DSAlgo/tree/main/14_Queue)
- [x] [**Greedy**](https://github.com/SamirPaulb/DSAlgo/tree/main/15_Greedy)
- [x] [**String**](https://github.com/SamirPaulb/DSAlgo/tree/main/16_String)
- [x] [**Bit Manipulation**](https://github.com/SamirPaulb/DSAlgo/tree/main/17_Bit-Manipulation)
- [x] [**Array**](https://github.com/SamirPaulb/DSAlgo/tree/main/18_Array)
- [x] [**HashMap**](https://github.com/SamirPaulb/DSAlgo/tree/main/19_HashMap)
- [x] [**DFS BFS**](https://github.com/SamirPaulb/DSAlgo/tree/main/20_DFS-BFS)
- [x] [**Two Pointers**](https://github.com/SamirPaulb/DSAlgo/tree/main/21_Two-Pointers)
- [x] [**Math**](https://github.com/SamirPaulb/DSAlgo/tree/main/22_Math)
- [x] [**Recursion**](https://github.com/SamirPaulb/DSAlgo/tree/main/23_Recursion)
In various folders of the above topics, you can find questions and concepts related to that topic.
- In the [Dynamic Programming](https://github.com/SamirPaulb/DSAlgo/tree/main/02_Dynamic-Programming) section, you can find all the questions covered and not covered in [Aditya Verma's](https://www.youtube.com/c/AdityaVermaTheProgrammingLord) [dynamic programming playlist](https://youtube.com/playlist?list=PL_z_8CaSLPWekqhdCPmFohncHwz8TY2Go) folder-wise with my [handwritten notes](https://drive.google.com/file/d/1wuMmJn2ybYN7eOYDXfe3gkB7TnpdGU3p/view?usp=sharing).✍️
- If you are preparing for an interview from [Striver’s SDE Sheet](https://takeuforward.org/interviews/strivers-sde-sheet-top-coding-interview-problems/) then the [**30-Days-SDE-Sheet-Practice**](https://github.com/SamirPaulb/DSAlgo/tree/main/30-Days-SDE-Sheet-Practice) will be helpful to you. Here I have stored solutions to questions of each day with short notes to each solution, as short notes about the approach are very helpful during revision.🎯
- In the [**Questions-Sheet**](https://github.com/SamirPaulb/DSAlgo/tree/main/Questions-Sheet) directory, you can find questions asked by top product-based companies.
- There is a collection of books and pdfs on various important computer science fundamentals in the [**BOOKS-and-PDFs**](https://github.com/SamirPaulb/DSAlgo/tree/main/BOOKS-and-PDFs) directory.đź“š
I am continuously trying to improve this repository by adding new questions and concepts related to the respective topic. Please feel free to contribute to this repository.
**Things you can contribute to:**
- Update the existing solution 
with a better one (better complexity).
- Add new questions and solutions in ```Python3``` to the respective directory.
- Add new resources to [BOOKS-and-PDFs](https://github.com/SamirPaulb/DSAlgo/tree/main/BOOKS-and-PDFs) & [Questions-Sheet](https://github.com/SamirPaulb/DSAlgo/tree/main/Questions-Sheet).
- Solve issues raised by other people or yourself.
- Provide well-documented source code with detailed explanations.
#### Stargazers over time
---
### More Resources:
> ***Click to expand!👇***
List of Important Questions:✨
> The following list of questions was recommended by [Love Babbar](https://www.youtube.com/c/LoveBabbar1) on this [video](https://youtu.be/4iFALQ1ACdA). I have documented all those questions here.✌️
| Topic | Important DSA Questions | Link |
|------------------------------|------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------|
| Topic: | Problem: | Related Link |
| <-> | | |
| Array | Reverse the array (char) | https://leetcode.com/problems/reverse-string/ |
| Array | Remove the maximum and minimum element in an array | https://leetcode.com/problems/removing-minimum-and-maximum-from-array/ |
| Array | Find the "Kth" largest element of an array | https://leetcode.com/problems/kth-largest-element-in-an-array/ |
| Array | Given an array which consists of only 0, 1 and 2. Sort the array without using any sorting algo | https://leetcode.com/problems/sort-colors/ |
| Array | Move all the negative elements to one side of the array | <-> |
| Array | Find the Union and Intersection of the two sorted arrays. | [Intersection of the two sorted arrays.(Leetcode)](https://leetcode.com/problems/intersection-of-two-arrays/) |
| Array | Write a program to cyclically rotate an array by one. | https://leetcode.com/problems/rotate-array/ |
| Array | find Largest sum contiguous Subarray [V. IMP] | https://leetcode.com/problems/maximum-subarray/ |
| Array | Minimise the maximum difference between heights [V.IMP] | https://leetcode.com/problems/smallest-range-ii/ |
| Array | Minimum no. of Jumps to reach end of an array | https://leetcode.com/problems/jump-game |
| Array | Find duplicate in an array of N+1 Integers | https://leetcode.com/problems/find-the-duplicate-number/ |
| Array | Merge 2 sorted arrays without using Extra space. | https://leetcode.com/problems/merge-sorted-array/
| Array | Kadane's Algorithm | https://leetcode.com/problems/maximum-subarray/ |
| Array | Merge Intervals | <-> |
| Array | Next Permutation | <-> |
| Array | Count Inversion | <-> |
| Array | Best time to buy and Sell stock | <-> |
| Array | find duplicate in an array of N+1 Integers | <-> |
| Array | Merge 2 sorted arrays without using Extra space. | <-> |
| Array | Kadane's Algorithm | https://leetcode.com/problems/maximum-subarray/ |
| Array | Merge Intervals | https://leetcode.com/problems/merge-intervals/ |
| Array | Next Permutation | https://leetcode.com/problems/next-permutation/ |
| Array | Count Inversions | <-> |
| Array | Best time to buy and Sell stock | https://leetcode.com/problems/best-time-to-buy-and-sell-stock/ |
| Array | find all pairs on integer array whose sum is equal to given number | <-> |
| Array | find common elements In 3 sorted arrays | <-> |
| Array | Rearrange the array in alternating positive and negative items with O(1) extra space | <-> |
| Array | Find if there is any subarray with sum equal to 0 | https://leetcode.com/problems/subarray-sum-equals-k/ |
| Array | Find factorial of a large number | <-> |
| Array | find maximum product subarray | <-> |
| Array | Find longest coinsecutive subsequence | <-> |
| Array | Given an array of size n and a number k, fin all elements that appear more than " n/k " times. | <-> |
| Array | Maximum profit by buying and selling a share atmost twice | <-> |
| Array | Find whether an array is a subset of another array | <-> |
| Array | Find the triplet that sum to a given value | <-> |
| Array | Trapping Rain water problem | <-> |
| Array | Chocolate Distribution problem | <-> |
| Array | Smallest Subarray with sum greater than a given value | <-> |
| Array | Three way partitioning of an array around a given value | <-> |
| Array | Minimum swaps required bring elements less equal K together | <-> |
| Array | Minimum no. of operations required to make an array palindrome | <-> |
| Array | Median of 2 sorted arrays of equal size | <-> |
| Array | Median of 2 sorted arrays of different size | <-> |
| Array | Subarray Sums Divisible by K | |
| Array | Continuous Subarray Sum | |
| <-> | | |
| <-> | | |
| Matrix | Spiral traversal on a Matrix | <-> |
| Matrix | Search an element in a matriix | <-> |
| Matrix | Find median in a row wise sorted matrix | <-> |
| Matrix | Find row with maximum no. of 1's | <-> |
| Matrix | Print elements in sorted order using row-column wise sorted matrix | <-> |
| Matrix | Largest Rectangle in Histogram | |
| Matrix | Maximum size rectangle | https://practice.geeksforgeeks.org/problems/max-rectangle/1 |
| Matrix | Find a specific pair in matrix | <-> |
| Matrix | Rotate matrix by 90 degrees | <-> |
| Matrix | Kth smallest element in a row-cpumn wise sorted matrix | <-> |
| Matrix | Common elements in all rows of a given matrix | <-> |
| String | Reverse a String | <-> |
| String | Check whether a String is Palindrome or not | <-> |
| String | Find Duplicate characters in a string | <-> |
| String | Why strings are immutable in Java? | <-> |
| String | Write a Code to check whether one string is a rotation of another | <-> |
| String | Write a Program to check whether a string is a valid shuffle of two strings or not | <-> |
| String | Count and Say problem | <-> |
| String | Write a program to find the longest Palindrome in a string.[ Longest palindromic Substring] | <-> |
| String | Find Longest Recurring Subsequence in String | <-> |
| String | Print all Subsequences of a string. | <-> |
| String | Print all the permutations of the given string | <-> |
| String | Split the Binary string into two substring with equal 0’s and 1’s | <-> |
| String | Word Wrap Problem [VERY IMP]. | <-> |
| String | EDIT Distance [Very Imp] | <-> |
| String | Find next greater number with same set of digits. [Very Very IMP] | <-> |
| String | Balanced Parenthesis problem.[Imp] | <-> |
| String | Word break Problem[ Very Imp] | <-> |
| String | Rabin Karp Algo | <-> |
| String | KMP Algo | <-> |
| String | Convert a Sentence into its equivalent mobile numeric keypad sequence. | <-> |
| String | Minimum number of bracket reversals needed to make an expression balanced. | <-> |
| String | Count All Palindromic Subsequence in a given String. | <-> |
| String | Count of number of given string in 2D character array | <-> |
| String | Search a Word in a 2D Grid of characters. | <-> |
| String | Boyer Moore Algorithm for Pattern Searching. | <-> |
| String | Converting Roman Numerals to Decimal | <-> |
| String | Longest Common Prefix | <-> |
| String | Number of flips to make binary string alternate | <-> |
| String | Find the first repeated word in string. | <-> |
| String | Minimum number of swaps for bracket balancing. | <-> |
| String | Find the longest common subsequence between two strings. | <-> |
| String | Program to generate all possible valid IP addresses from given string. | <-> |
| String | Write a program tofind the smallest window that contains all characters of string itself. | <-> |
| String | Rearrange characters in a string such that no two adjacent are same | <-> |
| String | Minimum characters to be added at front to make string palindrome | <-> |
| String | Given a sequence of words, print all anagrams together | <-> |
| String | Find the smallest window in a string containing all characters of another string | <-> |
| String | Recursively remove all adjacent duplicates | <-> |
| String | String matching where one string contains wildcard characters | <-> |
| String | Function to find Number of customers who could not get a computer | <-> |
| String | Transform One String to Another using Minimum Number of Given Operation | <-> |
| String | Check if two given strings are isomorphic to each other | <-> |
| String | Recursively print all sentences that can be formed from list of word lists | <-> |
| Searching & Sorting | Find first and last positions of an element in a sorted array | <-> |
| Searching & Sorting | Find a Fixed Point (Value equal to index) in a given array | https://leetcode.com/problems/find-pivot-index/ |
| Searching & Sorting | Search in a rotated sorted array | https://leetcode.com/problems/search-in-rotated-sorted-array/ |
| Searching & Sorting | square root of an integer | <-> |
| Searching & Sorting | Maximum and minimum of an array using minimum number of comparisons | <-> |
| Searching & Sorting | Optimum location of point to minimize total distance | https://leetcode.com/problems/best-meeting-point/ |
| Searching & Sorting | Find the repeating and the missing | <-> |
| Searching & Sorting | find majority element | <-> |
| Searching & Sorting | Searching in an array where adjacent differ by at most k | <-> |
| Searching & Sorting | find a pair with a given difference | <-> |
| Searching & Sorting | find four elements that sum to a given value | <-> |
| Searching & Sorting | maximum sum such that no 2 elements are adjacent | <-> |
| Searching & Sorting | Count triplet with sum smaller than a given value | <-> |
| Searching & Sorting | merge 2 sorted arrays | <-> |
| Searching & Sorting | print all subarrays with 0 sum | <-> |
| Searching & Sorting | Product array Puzzle | <-> |
| Searching & Sorting | Sort array according to count of set bits | <-> |
| Searching & Sorting | minimum no. of swaps required to sort the array | <-> |
| Searching & Sorting | Bishu and Soldiers | <-> |
| Searching & Sorting | Rasta and Kheshtak | <-> |
| Searching & Sorting | Kth smallest number again | Using Min Heap |
| Searching & Sorting | Find pivot element in a sorted array | <-> |
| Searching & Sorting | K-th Element of Two Sorted Arrays | <-> |
| Searching & Sorting | Aggressive cows | <-> |
| Searching & Sorting | Book Allocation Problem | https://leetcode.com/problems/capacity-to-ship-packages-within-d-days/ |
| Searching & Sorting | EKOSPOJ: | <-> |
| Searching & Sorting | Job Scheduling Algo | <-> |
| Searching & Sorting | Missing Number in AP | <-> |
| Searching & Sorting | Smallest number with atleastn trailing zeroes infactorial | <-> |
| Searching & Sorting | Painters Partition Problem: | <-> |
| Searching & Sorting | ROTI-Prata SPOJ | <-> |
| Searching & Sorting | DoubleHelix SPOJ | <-> |
| Searching & Sorting | Subset Sums | <-> |
| Searching & Sorting | Findthe inversion count | <-> |
| Searching & Sorting | Implement Merge-sort in-place | <-> |
| Searching & Sorting | Partitioning and Sorting Arrays with Many Repeated Entries | <-> |
| LinkedList | Write a Program to reverse the Linked List. (Both Iterative and recursive) | <-> |
| LinkedList | Reverse a Linked List in group of Given Size. [Very Imp] | https://leetcode.com/problems/reverse-nodes-in-k-group/ |
| LinkedList | Write a program to Detect loop in a linked list. | <-> |
| LinkedList | Write a program to Delete loop in a linked list. | <-> |
| LinkedList | Find the starting point of the loop. | <-> |
| LinkedList | Remove Duplicates in a sorted Linked List. | |
| LinkedList | Remove Duplicates from Sorted List II | |
| LinkedList | Remove Duplicates in a Un-sorted Linked List. | |
| LinkedList | Write a Program to Move the last element to Front in a Linked List. | <-> |
| LinkedList | Add “1” to a number represented as a Linked List. | <-> |
| LinkedList | Add two numbers represented by linked lists. | <-> |
| LinkedList | Intersection of two Sorted Linked List. | <-> |
| LinkedList | Intersection Point of two Linked Lists. | <-> |
| LinkedList | Merge Sort For Linked lists.[Very Important] | <-> |
| LinkedList | Quicksort for Linked Lists.[Very Important] | <-> |
| LinkedList | Find the middle Element of a linked list. | <-> |
| LinkedList | Check if a linked list is a circular linked list. | <-> |
| LinkedList | Split a Circular linked list into two halves. | <-> |
| LinkedList | Write a Program to check whether the Singly Linked list is a palindrome or not. | <-> |
| LinkedList | Deletion from a Circular Linked List. | <-> |
| LinkedList | Reverse a Doubly Linked list. | <-> |
| LinkedList | Find pairs with a given sum in a DLL. | <-> |
| LinkedList | Count triplets in a sorted DLL whose sum is equal to given value “X”. | <-> |
| LinkedList | Sort a “k”sorted Doubly Linked list.[Very IMP] | <-> |
| LinkedList | Rotate DoublyLinked list by N nodes. | <-> |
| LinkedList | Rotate a Doubly Linked list in group of Given Size.[Very IMP] | <-> |
| LinkedList | Can we reverse a linked list in less than O(n) ? | <-> |
| LinkedList | Why Quicksort is preferred for. Arrays and Merge Sort for LinkedLists ? | <-> |
| LinkedList | Flatten a Linked List | <-> |
| LinkedList | Sort a LL of 0's, 1's and 2's | <-> |
| LinkedList | Clone a linked list with next and random pointer | <-> |
| LinkedList | Merge K sorted Linked list | <-> |
| LinkedList | Multiply 2 no. represented by LL | <-> |
| LinkedList | Delete nodes which have a greater value on right side | <-> |
| LinkedList | Segregate even and odd nodes in a Linked List | <-> |
| LinkedList | Program for n’th node from the end of a Linked List | <-> |
| LinkedList | Find the first non-repeating character from a stream of characters | <-> |
| Binary Trees | level order traversal | <-> |
| Binary Trees | Reverse Level Order traversal | <-> |
| Binary Trees | Height of a tree | <-> |
| Binary Trees | Diameter of a tree | <-> |
| Binary Trees | Mirror of a tree | <-> |
| Binary Trees | Inorder Traversal of a tree both using recursion and Iteration | <-> |
| Binary Trees | Preorder Traversal of a tree both using recursion and Iteration | <-> |
| Binary Trees | Postorder Traversal of a tree both using recursion and Iteration | <-> |
| Binary Trees | Left View of a tree | <-> |
| Binary Trees | Right View of Tree | https://leetcode.com/problems/binary-tree-right-side-view/ |
| Binary Trees | Top View of a tree | https://leetcode.com/problems/vertical-order-traversal-of-a-binary-tree/ |
| Binary Trees | Bottom View of a tree | <-> |
| Binary Trees | Zig-Zag traversal of a binary tree | https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/ |
| Binary Trees | Check if a tree is balanced or not | <-> |
| Binary Trees | Diagnol Traversal of a Binary tree | https://www.youtube.com/watch?v=e9ZGxH1y_PE |
| Binary Trees | Boundary traversal of a Binary tree | https://www.youtube.com/watch?v=0ca1nvR0be4 |
| Binary Trees | Construct Binary Tree from String with Bracket Representation | <-> |
| Binary Trees | Convert Binary tree into Doubly Linked List | <-> |
| Binary Trees | Convert Binary tree into Sum tree | <-> |
| Binary Trees | Construct Binary tree from Inorder and preorder traversal | <-> |
| Binary Trees | Find minimum swaps required to convert a Binary tree into BST | <-> |
| Binary Trees | Check if Binary tree is Sum tree or not | <-> |
| Binary Trees | Check if all leaf nodes are at same level or not | <-> |
| Binary Trees | Check if a Binary Tree contains duplicate subtrees of size 2 or more [ IMP ] | <-> |
| Binary Trees | Check if 2 trees are mirror or not | <-> |
| Binary Trees | Sum of Nodes on the Longest path from root to leaf node | <-> |
| Binary Trees | Check if given graph is tree or not. [ IMP ] | <-> |
| Binary Trees | Find Largest subtree sum in a tree | <-> |
| Binary Trees | Maximum Sum of nodes in Binary tree such that no two are adjacent | <-> |
| Binary Trees | Print all "K" Sum paths in a Binary tree | <-> |
| Binary Trees | Find LCA in a Binary tree | <-> |
| Binary Trees | Find distance between 2 nodes in a Binary tree | <-> |
| Binary Trees | Kth Ancestor of node in a Binary tree | <-> |
| Binary Trees | Find all Duplicate subtrees in a Binary tree [ IMP ] | <-> |
| Binary Trees | Tree Isomorphism Problem | <-> |
| Binary Trees | Copy List with Random Pointer | |
| Binary Search Trees | Fina a value in a BST | <-> |
| Binary Search Trees | Deletion of a node in a BST | <-> |
| Binary Search Trees | Find min and max value in a BST | <-> |
| Binary Search Trees | Find inorder successor and inorder predecessor in a BST | <-> |
| Binary Search Trees | Check if a tree is a BST or not | <-> |
| Binary Search Trees | Populate Inorder successor of all nodes | <-> |
| Binary Search Trees | Find LCA of 2 nodes in a BST | <-> |
| Binary Search Trees | Construct BST from preorder traversal | <-> |
| Binary Search Trees | Convert Binary tree into BST | <-> |
| Binary Search Trees | Convert a normal BST into a Balanced BST | <-> |
| Binary Search Trees | Merge two BST [ V.V.V>IMP ] | <-> |
| Binary Search Trees | Find Kth largest element in a BST | <-> |
| Binary Search Trees | Find Kth smallest element in a BST | <-> |
| Binary Search Trees | Count pairs from 2 BST whose sum is equal to given value "X" | <-> |
| Binary Search Trees | Find the median of BST in O(n) time and O(1) space | <-> |
| Binary Search Trees | Count BST ndoes that lie in a given range | <-> |
| Binary Search Trees | Replace every element with the least greater element on its right | <-> |
| Binary Search Trees | Given "n" appointments, find the conflicting appointments | <-> |
| Binary Search Trees | Check preorder is valid or not | <-> |
| Binary Search Trees | Check whether BST contains Dead end | <-> |
| Binary Search Trees | Largest BST in a Binary Tree [ V.V.V.V.V IMP ] | <-> |
| Binary Search Trees | Flatten BST to sorted list | <-> |
| Binary Search Trees | Check Completeness of a Binary Tree | |
| Binary Search Trees | Non-overlapping Intervals | |
| Binary Search Trees | Largest BST in Binary Tree | https://leetcode.com/problems/maximum-sum-bst-in-binary-tree/ |
| Greedy | Activity Selection Problem | <-> |
| Greedy | Job SequencingProblem | <-> |
| Greedy | Huffman Coding | <-> |
| Greedy | Water Connection Problem | <-> |
| Greedy | Fractional Knapsack Problem | <-> |
| Greedy | Greedy Algorithm to find Minimum number of Coins | <-> |
| Greedy | Maximum trains for which stoppage can be provided | <-> |
| Greedy | Minimum Platforms Problem | <-> |
| Greedy | Buy Maximum Stocks if i stocks can be bought on i-th day | <-> |
| Greedy | Find the minimum and maximum amount to buy all N candies | <-> |
| Greedy | Minimize Cash Flow among a given set of friends who have borrowed money from each other | Optimal Account Balancing |
| Greedy | Minimum Cost to cut a board into squares | <-> |
| Greedy | Number of Islands | <-> |
| Greedy | Find maximum meetings in one room | https://www.lintcode.com/problem/919 |
| Greedy | Maximum product subset of an array | <-> |
| Greedy | Maximize array sum after K negations | <-> |
| Greedy | Maximize the sum of arr[i]*i | <-> |
| Greedy | Maximum sum of absolute difference of an array | <-> |
| Greedy | Maximize sum of consecutive differences in a circular array | <-> |
| Greedy | Minimum sum of absolute difference of pairs of two arrays | <-> |
| Greedy | Program for Shortest Job First (or SJF) CPU Scheduling | <-> |
| Greedy | Program for Least Recently Used (LRU) Page Replacement algorithm | <-> |
| Greedy | Smallest subset with sum greater than all other elements | <-> |
| Greedy | Chocolate Distribution Problem | <-> |
| Greedy | DEFKIN -Defense of a Kingdom | <-> |
| Greedy | DIEHARD -DIE HARD | <-> |
| Greedy | GERGOVIA -Wine trading in Gergovia | <-> |
| Greedy | Picking Up Chicks | <-> |
| Greedy | CHOCOLA –Chocolate | <-> |
| Greedy | ARRANGE -Arranging Amplifiers | <-> |
| Greedy | K Centers Problem | <-> |
| Greedy | Minimum Cost of ropes | <-> |
| Greedy | Find smallest number with given number of digits and sum of digits | <-> |
| Greedy | Rearrange characters in a string such that no two adjacent are same | <-> |
| Greedy | Find maximum sum possible equal sum of three stacks | <-> |
| Greedy | Maximum Sub-String after at most K changes | https://leetcode.com/problems/maximize-the-confusion-of-an-exam/ |
| BackTracking | Rat in a maze Problem | <-> |
| BackTracking | Printing all solutions in N-Queen Problem | <-> |
| BackTracking | Word Break Problem using Backtracking | <-> |
| BackTracking | Remove Invalid Parentheses | <-> |
| BackTracking | Sudoku Solver | <-> |
| BackTracking | m Coloring Problem | <-> |
| BackTracking | Print all palindromic partitions of a string | <-> |
| BackTracking | Subset Sum Problem | <-> |
| BackTracking | The Knight’s tour problem | <-> |
| BackTracking | Tug of War | <-> |
| BackTracking | Find shortest safe route in a path with landmines | <-> |
| BackTracking | Combinational Sum | <-> |
| BackTracking | Find Maximum number possible by doing at-most K swaps | <-> |
| BackTracking | Print all permutations of a string | <-> |
| BackTracking | Find if there is a path of more than k length from a source | <-> |
| BackTracking | Longest Possible Route in a Matrix with Hurdles | <-> |
| BackTracking | Print all possible paths from top left to bottom right of a mXn matrix | <-> |
| BackTracking | Partition of a set intoK subsets with equal sum | <-> |
| BackTracking | Find the K-th Permutation Sequence of first N natural numbers | <-> |
| Stacks & Queues | Implement Stack from Scratch | <-> |
| Stacks & Queues | Implement Queue from Scratch | <-> |
| Stacks & Queues | Implement 2 stack in an array | <-> |
| Stacks & Queues | find the middle element of a stack | <-> |
| Stacks & Queues | Implement "N" stacks in an Array | <-> |
| Stacks & Queues | Check the expression has valid or Balanced parenthesis or not. | <-> |
| Stacks & Queues | Reverse a String using Stack | <-> |
| Stacks & Queues | Design a Stack that supports getMin() in O(1) time and O(1) extra space. | <-> |
| Stacks & Queues | Find the next Greater element | <-> |
| Stacks & Queues | The celebrity Problem | https://www.youtube.com/watch?v=CiiXBvrX-5A |
| Stacks & Queues | Arithmetic Expression evaluation | https://leetcode.com/problems/evaluate-reverse-polish-notation/ |
| Stacks & Queues | Evaluation of Postfix expression | https://www.youtube.com/watch?v=422Q_yx2yA8 |
| Stacks & Queues | Implement a method to insert an element at its bottom without using any other data structure. | <-> |
| Stacks & Queues | Reverse a stack using recursion | <-> |
| Stacks & Queues | Sort a Stack using recursion | <-> |
| Stacks & Queues | Merge Overlapping Intervals | <-> |
| Stacks & Queues | Largest rectangular Area in Histogram | <-> |
| Stacks & Queues | Length of the Longest Valid Substring | <-> |
| Stacks & Queues | Expression contains redundant bracket or not | <-> |
| Stacks & Queues | Implement Stack using Queue | <-> |
| Stacks & Queues | Implement Stack using Deque | <-> |
| Stacks & Queues | Stack Permutations (Check if an array is stack permutation of other) | <-> |
| Stacks & Queues | Implement Queue using Stack | <-> |
| Stacks & Queues | Implement "n" queue in an array | <-> |
| Stacks & Queues | Implement a Circular queue | <-> |
| Stacks & Queues | LRU Cache Implementationa | <-> |
| Stacks & Queues | Reverse a Queue using recursion | <-> |
| Stacks & Queues | Reverse the first “K” elements of a queue | <-> |
| Stacks & Queues | Interleave the first half of the queue with second half | <-> |
| Stacks & Queues | Find the first circular tour that visits all Petrol Pumps | <-> |
| Stacks & Queues | Minimum time required to rot all oranges | <-> |
| Stacks & Queues | Distance of nearest cell having 1 in a binary matrix | <-> |
| Stacks & Queues | First negative integer in every window of size “k” | <-> |
| Stacks & Queues | Check if all levels of two trees are anagrams or not. | <-> |
| Stacks & Queues | Sum of minimum and maximum elements of all subarrays of size “k”. | <-> |
| Stacks & Queues | Minimum sum of squares of character counts in a given string after removing “k” characters. | <-> |
| Stacks & Queues | Queue based approach or first non-repeating character in a stream. | <-> |
| Stacks & Queues | Next Smaller Element | <-> |
| Heap | Implement a Maxheap/MinHeap using arrays and recursion. | <-> |
| Heap | Sort an Array using heap. (HeapSort) | <-> |
| Heap | Maximum of all subarrays of size k. | <-> |
| Heap | “k” largest element in an array | <-> |
| Heap | Kth smallest and largest element in an unsorted array | <-> |
| Heap | Merge “K” sorted arrays. [ IMP ] | <-> |
| Heap | Merge 2 Binary Max Heaps | <-> |
| Heap | Kth largest sum continuous subarrays | <-> |
| Heap | Leetcode- reorganize strings | <-> |
| Heap | Merge “K” Sorted Linked Lists [V.IMP] | <-> |
| Heap | Smallest range in “K” Lists | <-> |
| Heap | Median in a stream of Integers | <-> |
| Heap | Check if a Binary Tree is Heap | <-> |
| Heap | Connect “n” ropes with minimum cost | <-> |
| Heap | Convert BST to Min Heap | <-> |
| Heap | Convert min heap to max heap | <-> |
| Heap | Rearrange characters in a string such that no two adjacent are same. | <-> |
| Heap | Minimum sum of two numbers formed from digits of an array | <-> |
| Graph | Create a Graph, print it | <-> |
| Graph | Implement BFS algorithm | <-> |
| Graph | Implement DFS Algo | <-> |
| Graph | Detect Cycle in Directed Graph using BFS/DFS Algo | <-> |
| Graph | Detect Cycle in UnDirected Graph using BFS/DFS Algo | <-> |
| Graph | Search in a Maze | <-> |
| Graph | Minimum Step by Knight | <-> |
| Graph | flood fill algo | <-> |
| Graph | Clone a graph | <-> |
| Graph | Making wired Connections | <-> |
| Graph | word Ladder | <-> |
| Graph | Dijkstra algo | <-> |
| Graph | Implement Topological Sort | <-> |
| Graph | Minimum time taken by each job to be completed given by a Directed Acyclic Graph | <-> |
| Graph | Find whether it is possible to finish all tasks or not from given dependencies | <-> |
| Graph | Find the no. of Isalnds | <-> |
| Graph | Given a sorted Dictionary of an Alien Language, find order of characters | <-> |
| Graph | Implement Kruksal’sAlgorithm | <-> |
| Graph | Implement Prim’s Algorithm | <-> |
| Graph | Total no. of Spanning tree in a graph | <-> |
| Graph | Implement Bellman Ford Algorithm | <-> |
| Graph | Implement Floyd warshallAlgorithm | <-> |
| Graph | Travelling Salesman Problem | <-> |
| Graph | Graph ColouringProblem | <-> |
| Graph | Snake and Ladders Problem | <-> |
| Graph | Find bridge in a graph | <-> |
| Graph | Count Strongly connected Components(Kosaraju Algo) | <-> |
| Graph | Check whether a graph is Bipartite or Not | <-> |
| Graph | Detect Negative cycle in a graph | <-> |
| Graph | Longest path in a Directed Acyclic Graph | <-> |
| Graph | Journey to the Moon | <-> |
| Graph | Cheapest Flights Within K Stops | <-> |
| Graph | Oliver and the Game | <-> |
| Graph | Water Jug problem using BFS | <-> |
| Graph | Water Jug problem using BFS | <-> |
| Graph | Find if there is a path of more thank length from a source | <-> |
| Graph | M-ColouringProblem | <-> |
| Graph | Minimum edges to reverse o make path from source to destination | <-> |
| Graph | Paths to travel each nodes using each edge(Seven Bridges) | <-> |
| Graph | Vertex Cover Problem | <-> |
| Graph | Chinese Postman or Route Inspection | <-> |
| Graph | Number of Triangles in a Directed and Undirected Graph | <-> |
| Graph | Minimise the cashflow among a given set of friends who have borrowed money from each other | <-> |
| Graph | Two Clique Problem | <-> |
| Trie | Construct a trie from scratch | <-> |
| Trie | Find shortest unique prefix for every word in a given list | <-> |
| Trie | Word Break Problem | (Trie solution) | <-> |
| Trie | Given a sequence of words, print all anagrams together | <-> |
| Trie | Implement a Phone Directory | <-> |
| Trie | Print unique rows in a given boolean matrix | <-> |
| Dynamic Programming | Coin ChangeProblem | <-> |
| Dynamic Programming | Knapsack Problem | <-> |
| Dynamic Programming | Binomial CoefficientProblem | <-> |
| Dynamic Programming | Permutation CoefficientProblem | <-> |
| Dynamic Programming | Program for nth Catalan Number | <-> |
| Dynamic Programming | Matrix Chain Multiplication | <-> |
| Dynamic Programming | Edit Distance | <-> |
| Dynamic Programming | Subset Sum Problem | <-> |
| Dynamic Programming | Friends Pairing Problem | <-> |
| Dynamic Programming | Gold Mine Problem | <-> |
| Dynamic Programming | Assembly Line SchedulingProblem | <-> |
| Dynamic Programming | Painting the Fenceproblem | <-> |
| Dynamic Programming | Maximize The Cut Segments | <-> |
| Dynamic Programming | Longest Common Subsequence | <-> |
| Dynamic Programming | Longest Repeated Subsequence | <-> |
| Dynamic Programming | Longest Increasing Subsequence | <-> |
| Dynamic Programming | Space Optimized Solution of LCS | <-> |
| Dynamic Programming | LCS (Longest Common Subsequence) of three strings | <-> |
| Dynamic Programming | Maximum Sum Increasing Subsequence | <-> |
| Dynamic Programming | Count all subsequences having product less than K | <-> |
| Dynamic Programming | Longest subsequence such that difference between adjacent is one | <-> |
| Dynamic Programming | Maximum subsequence sum such that no three are consecutive | <-> |
| Dynamic Programming | Egg Dropping Problem | <-> |
| Dynamic Programming | Maximum Length Chain of Pairs | <-> |
| Dynamic Programming | Maximum size square sub-matrix with all 1s | <-> |
| Dynamic Programming | Maximum sum of pairs with specific difference | <-> |
| Dynamic Programming | Min Cost PathProblem | <-> |
| Dynamic Programming | Maximum difference of zeros and ones in binary string | <-> |
| Dynamic Programming | Minimum number of jumps to reach end | <-> |
| Dynamic Programming | Minimum cost to fill given weight in a bag | <-> |
| Dynamic Programming | Minimum removals from array to make max –min <= K | <-> |
| Dynamic Programming | Longest Common Substring | <-> |
| Dynamic Programming | Count number of ways to reacha given score in a game | <-> |
| Dynamic Programming | Count Balanced Binary Trees of Height h | <-> |
| Dynamic Programming | LargestSum Contiguous Subarray [V>V>V>V IMP ] | <-> |
| Dynamic Programming | Smallest sum contiguous subarray | <-> |
| Dynamic Programming | Unbounded Knapsack (Repetition of items allowed) | <-> |
| Dynamic Programming | Word Break Problem | <-> |
| Dynamic Programming | Largest Independent Set Problem | <-> |
| Dynamic Programming | Partition problem | <-> |
| Dynamic Programming | Longest Palindromic Subsequence | <-> |
| Dynamic Programming | Count All Palindromic Subsequence in a given String | <-> |
| Dynamic Programming | Longest Palindromic Substring | <-> |
| Dynamic Programming | Longest alternating subsequence | <-> |
| Dynamic Programming | Weighted Job Scheduling | <-> |
| Dynamic Programming | Coin game winner where every player has three choices | <-> |
| Dynamic Programming | Count Derangements (Permutation such that no element appears in its original position) [ IMPORTANT ] | <-> |
| Dynamic Programming | Maximum profit by buying and selling a share at most twice [ IMP ] | <-> |
| Dynamic Programming | Optimal Strategy for a Game | <-> |
| Dynamic Programming | Optimal Binary Search Tree | <-> |
| Dynamic Programming | Palindrome PartitioningProblem | <-> |
| Dynamic Programming | Word Wrap Problem | <-> |
| Dynamic Programming | Mobile Numeric Keypad Problem [ IMP ] | <-> |
| Dynamic Programming | Boolean Parenthesization Problem | <-> |
| Dynamic Programming | Largest rectangular sub-matrix whose sum is 0 | <-> |
| Dynamic Programming | Largest area rectangular sub-matrix with equal number of 1’s and 0’s [ IMP ] | <-> |
| Dynamic Programming | Maximum sum rectangle in a 2D matrix | <-> |
| Dynamic Programming | Maximum profit by buying and selling a share at most k times | <-> |
| Dynamic Programming | Find if a string is interleaved of two other strings | <-> |
| Dynamic Programming | Maximum Length of Pair Chain | <-> |
| Dynamic Programming | Partition Equal Subset Sum | https://leetcode.com/submissions/detail/561942165/ |
| Dynamic Programming | Target Sum | |
| Bit Manipulation | Count set bits in an integer | <-> |
| Bit Manipulation | Find the two non-repeating elements in an array of repeating elements | <-> |
| Bit Manipulation | Count number of bits to be flipped to convert A to B | <-> |
| Bit Manipulation | Count total set bits in all numbers from 1 to n | <-> |
| Bit Manipulation | Program to find whether a no is power of two | <-> |
| Bit Manipulation | Find position of the only set bit | <-> |
| Bit Manipulation | Copy set bits in a range | <-> |
| Bit Manipulation | Divide two integers without using multiplication, division and mod operator | <-> |
| Bit Manipulation | Calculate square of a number without using *, / and pow() | <-> |
| Bit Manipulation | Power Set | <-> |
| Moore voting algorithm | Majority Element | https://www.youtube.com/watch?v=n5QY3x_GNDg |
| Moore voting algorithm | Majority Element II | https://www.youtube.com/watch?v=yDbkQd9t2ig |
30 Days Interview Preparation Plan:🎯
https://github.com/SamirPaulb/DSAlgo/tree/main/30-Days-SDE-Sheet-Practice
> Originally the below sheet was prepared by [Raj Vikramaditya](https://www.youtube.com/c/takeUforward) A.K.A [Striver](https://www.youtube.com/channel/UCvEKHATlVq84hm1jduTYm8g). I have documented this sheet here in markdown.
Day1: (Arrays)
1. Sort an array of 0’s 1’s 2’s without using extra space or sorting algo
2. Repeat and Missing Number
3. Merge two sorted Arrays without extra space
4. Kadane’s Algorithm
5. Merge Overlapping Subintervals
6. Find the duplicate in an array of N+1 integers.
Day2: (Arrays)
1. Set Matrix Zeros
2. Pascal Triangle
3. Next Permutation
4. Inversion of Array (Using Merge Sort)
5. Stock Buy and Sell
6. Ro tate Matrix
Day3: (Arrays/maths)
1. Search in a 2D matrix
2. Pow(X,n)
3. Majority Element (>N/2 times)
4. Majority Element (>N/3 times)
5. Grid Unique Paths
6. Reverse Pairs (Leetcode)
7. Go through Puzzles from GFG** (Search on own)
Day4: (Hashing)
1. 2 Sum problem
2. 4 Sum problem
3. Longest Consecutive Sequence
4. Largest Subarray with 0 sum
5. Count number of subarrays with given XOR (this clearsa lot of problems)
6. Longest substring without repeat
Day5: (LinkedList)
1. Reverse a LinkedList
2. Find middle of LinkedList
3. Merge two sorted Linked List
4. Remove N-th node from back of LinkedList
5. Delete a given Node when a node is given. (0(1) solution)
6. Add two numbers as LinkedList
Day6:
1. Find intersection point of Y LinkedList
2. Detect a cycle in Linked List
3. Reverse a LinkedList in groups of size k
4. Check if a LinkedList is palindrome or not.
5. Find the starting point of the Loop of LinkedList
6. Flattening of a LinkedList**
7. Rotate a LinkedList
Day7: (2-pointer)
1. Clone a Linked List with random and next pointer
2. 3 sum
3. Trapping rainwater
4. Remove Duplicate from Sorted array
5. Max consecutive ones
Day8: (Greedy)
1. N meeting in one room
2. Minimum number of platforms required for a railway
3. Job sequencing Problem
4. Fractional Knapsack Problem
5. Greedy algorithm to find minimum number of coins
6. Activity Selection (it i
8. s same as N meeting in one room)
Day9 (Recursion):
1. Subset Sums
2. Subset-II
3. Combination sum-
4. Combination sum
5. Palindrome Partitioning
6. K-th permutation Sequence
Day10: (Recursion and Backtracking)
1. Print all Permutations of a string/array
2. N queens Problem
3. SudokuSolver
4. M coloring Problem
5. Rat in a Maze
6.Word Break -> print all ways
Day11 : (Binary Search)
1. N-th root of an integer (use binary search) (square root, cube root, ..)
2. Matrix Median
3. Find the element that appears once in sorted array, and rest element appears twice (Binary search)
4. Search element in a sorted and rotated array/ find pivot where it is rotated**
5. Median of 2 sorted arrays
6. K-th element of two sorted arrays
7. Allocate Minimum Number of Pages
8. Aggressive Cows
Day12: (Bits) (Optional, very rare topic in interviews, but if you have time left, someone might
ask)
1. Check if a number if a power of 2 or not in O(1)
2. Count total set bits
3. Divide Integers without / operator
4. Power Set (this is very important)
5. Find MSB in o(1)
6. Find square of a number without using multiplication or division operators.
Day13: (Stack and Queue)
1. Implement Stack Using Arrays
2. Implement Queue Using Arrays
3. Implement Stack using Queue (using single queue)
4. Implement Queue using Stack (0(1) amortised method)
5. Check for balanced parentheses
6. Next Greater Element
7. Sort a Stack
Day14:
1. Next Smaller Element
Similar to previous question next greater element, just do pop the greater elements
out ..
2. LRU cache (vvvv. imp)
3. LFU Cache (Hard, can be ignored)
4.Largest rectangle in histogram (Do the one pass solution)
[Two pass](https://www.youtube.com/watch?v=X0X6G-eWgQ8&list=PLgUwDviBIf0p4ozDR_kJJkONnb1wdx2Ma&index=)
[One pass](https://www.youtube.com/watch?v=jC_cWLy7jSI&list=PLgUwDviBIf0p4ozDR_kJJkONnb1wdx2Ma&index=)
5. Sliding Window maximum [video](https://www.youtube.com/watch?v=CZQGRp93K4k&list=PLgUwDviBIf0p4ozDR_kJJkONnb1wdx2Ma&index=)
6. Implement Min Stack
7. Rotten Orange (Using BFS)
8. Stock Span Problem
9. Find maximum of minimums of every window size
10.The Celebrity Problem
Day15: (String)
1. Reverse Words in a String
2. Longest Palindrome in a string
3. Roman Number to Integer and vice versa
4. Implement ATOI/STRSTR
5. Longest Common Prefix
6. Rabin Karp
Day16: (String)
1. Prefix Function/Z-Function
2. KMP algo / LPS(pi) array
3. Minimum characters needed to be inserted in the beginning to make it palindromic.
4. Check for Anagrams
5. Count and Say
6. Compare version numbers
Day17: (Binary Tree)
1. Inorder Traversal (with recursion and without recursion)
2. Preorder Traversal (with recursion and without recursion)
3. Postorder Traversal (with recursion and without recursion)
4. LeftView Of Binary Tree
5. Bottom View of Binary Tree
6. Top View of Binary Tree**
Day18: (Binary Tree)
1. Level order Traversal / Level order traversal in spiral form
2. Height of a Binary Tree
3. Diameter of Binary Tree
4. Check if Binary tree is height balanced or not
5. LCA in Binary Tree
6. Check if two trees are identical or not**
Day 19: (Binary Tree)
1. Maximum path sum
2. Construct Binary Tree from inorder and preorder
3. Construct Binary Tree from Inorder and Postorder
4. Symmetric Binary Tree
5. Flatten Binary Tree to LinkedList
6. Check if Binary Tree is mirror of itself or not
Day 20: (Binary Search Tree)
1. Populate Next Right pointers of Tree
2. Search given Key in BST
3. Construct BST from given keys.
4. Check is a BT is BST or not
5. Find LCA of two nodes in BST
6. Find the inorder predecessor/successor of a given Key in BST.**
Day21: (BinarySearchTree)
1. Floor and Ceil in a BST
2. Find K-th smallest and K-th largest element in BST (2 different Questions)
3. Find a pair with a given sum in BST
4. BST iterator
5. Size of the largest BST in a Binary Tree
6. Serialize and deserialize Binary Tree
Day22: (Mixed Questions)
1. Binary Tree to Double Linked List
2. Find median in a stream of running integers.
3. K-th largest element in a stream.
4. Distinct numbers in Window.
5. K-th largest element in an unsorted array.
6. Flood-fill Algorithm
Day23: (Graph) [Theory](https://www.youtube.com/watch?v=LCrovIMurxY&list=PLgUwDviBIf0rGEWe64KWas0NrynSCRWw&index=)
1. Clone a graph (Not that easy as it looks)
2. DFS
3. BFS
4. Detect A cycle in Undirected Graph/Directed Graph
5. Topo Sort
6. Number of islands (Do in Grid and Graph both)
7. Bipartite Check
Day24: (Graph) [Theory](https://www.youtube.com/watch?v=LCrovIMurxY&list=PLgUwDviBIf0rGEWe64KWas0NrynSCRWw&index=)
1. SCC(using KosaRaju’s algo)
2. Djisktra’s Algorithm
3. Bellman Ford Algo
4. Floyd Warshall Algorithm
5. MST using Prim’s Algo
6. MST using Kruskal’s Algo
Day25: (Dynamic Programming)
1. Max Product Subarray
2. Longest Increasing Subsequence
3. Longest Common Subsequence
4. 0-1 Knapsack
5. Edit Distance
6. Maximum sum increasing subsequence
7. Matrix Chain Multiplication
Day26: (DP)
1. Maximum sum path in matrix, (count paths, and similar type do, also backtrack to find
the maximum path)
2. Coin change
3. Subset Sum
4. Rod Cutting
5. Egg Dropping
6. Word Break
7. Palindrome Partitioning (MCM Variation)
8. Maximum profit in Job scheduling
[For core revision](https://docs.google.com/document/d/1sQlRDw6--HwyxeFL7b4kBsOG-Tz7rXMbpWNnfvJErA4/edit)
Day27:
1. Revise OS notes that you would have made during your sem
2. If not made notes, spend 2 or 3 days and make notes from Knowledge Gate.
Day28:
1. Revise DBMS notes that you would have made during your semesters.
2. If not made notes, spend 2 or 3 days and make notes from Knowledge Gate.
Day29:
1. Revise CN notes, that you would have made during your sem.
2. If not made notes, spend 2 or 3 days and make notes from Knowledge Gate.
Day30:
1. Make a note of how will your represent your projects, and prepare all questions
related to tech which you have used in your projects. Prepare a note which you can
say for 3-10 minutes when he asks you that say something about the project.
System Design Concepts:đź“š
1. https://samirpaul.in/posts/system-design-course
2. **https://github.com/SamirPaulb/system-design**
3. https://www.freecodecamp.org/news/systems-design-for-interviews
4. https://www.geeksforgeeks.org/system-design-tutorial
5. https://youtube.com/playlist?list=PLMCXHnjXnTnvo6alSjVkgxV-VH6EPyvoX
