Soltuions to AlgoExpert Problems in C++ and Python with their optimal Space-Time Complexities.
- Arrays
- Binary Search Trees
- Binary Trees
- Dynamic Programming
- Famous Algorithms
- Graphs
- Greedy Algorithms
- Heaps
- Linked Lists
- Recursion
- Searching
- Sorting
- Stacks
- Strings
- Tries
- 🟩 - Easy
- 🟦 - Medium
- 🟥 - Hard
- ⬛ - Very Hard
| S.No | Problem | Difficulty Level | Category | Solutions |
|---|---|---|---|---|
| 1. | Two Number Sum | 🟩 | Arrays | [Link](/Easy/Two Number Sum) |
| 2. | Validate Subsequence | 🟩 | Arrays | [Link](/Easy/Validate Subsequence) |
| 3. | Sorted Squared Array | 🟩 | Arrays | [Link](/Easy/Sorted Squared Array) |
| 4. | Tournament Winner | 🟩 | Arrays | [Link](/Easy/Tournament Winner) |
| 5. | Non-Constructible Change | 🟩 | Arrays | [Link](/Easy/Non-Constructible Change) |
| 6. | Transpose Matrix | 🟩 | Arrays | [Link](/Easy/Transpose Matrix) |
| 7. | Three Number Sum | 🟦 | Arrays | [Link](/Medium/Three Number Sum) |
| 8. | Smallest Difference | 🟦 | Arrays | [Link](/Medium/Smallest Difference) |
| 9. | Move Element To End | 🟦 | Arrays | [Link](/Medium/Move Element To End) |
| 10. | Monotonic Array | 🟦 | Arrays | [Link](/Medium/Monotonic Array) |
| 11. | Spiral Traverse | 🟦 | Arrays | [Link](/Medium/Spiral Traverse) |
| 12. | Longest Peak | 🟦 | Arrays | [Link](/Medium/Longest Peak) |
| 13. | Array Of Products | 🟦 | Arrays | [Link](/Medium/Array Of Products) |
| 14. | First Duplicate Value | 🟦 | Arrays | [Link](/Medium/First Duplicate Value) |
| 15. | Merge Overlapping Intervals | 🟦 | Arrays | [Link](/Medium/Merge Overlapping Intervals) |
| 16. | Best Seat | 🟦 | Arrays | [Link](/Medium/Best Seat) |
| 17. | Zero Sum Subarray | 🟦 | Arrays | [Link](/Medium/Zero Sum Subarray) |
| 18. | Missing Numbers | 🟦 | Arrays | [Link](/Medium/Missing Numbers) |
| 19. | Majority Element | 🟦 | Arrays | [Link](/Medium/Majority Element) |
| 20. | Sweet And Savory | 🟦 | Arrays | [Link](/Medium/Sweet And Savory) |
| 21. | Four Number Sum | 🟥 | Arrays | [Link](/Hard/Four Number Sum) |
| 22. | Subarray Sort | 🟥 | Arrays | [Link](/Hard/Subarray Sort) |
| 23. | Largest Range | 🟥 | Arrays | [Link](/Hard/Largest Range) |
| 24. | Min Rewards | 🟥 | Arrays | [Link](/Hard/Min Rewards) |
| 25. | Zigzag Traverse | 🟥 | Arrays | [Link](/Hard/Zigzag Traverse) |
| 26. | Longest Subarray With Sum | 🟥 | Arrays | [Link](/Hard/Longest Subarray With Sum) |
| 27. | Knight Connection | 🟥 | Arrays | [Link](/Hard/Knight Connection) |
| 28. | Count Squares | 🟥 | Arrays | [Link](/Hard/Count Squares) |
| 29. | Apartment Hunting | ⬛ | Arrays | [Link](/Very Hard/Apartment Hunting) |
| 30. | Calendar Matching | ⬛ | Arrays | [Link](/Very Hard/Calendar Matching) |
| 31. | Waterfall Streams | ⬛ | Arrays | [Link](/Very Hard/Waterfall Streams) |
| 32. | Minimum Area Rectangle | ⬛ | Arrays | [Link](/Very Hard/Minimum Area Rectangle) |
| 33. | Line Through Points | ⬛ | Arrays | [Link](/Very Hard/Line Through Points) |
| 34. | Find Closest Value In BST | 🟩 | Binary Search Trees | [Link](/Easy/Find Closest Value In BST) |
| 35. | BST Construction | 🟦 | Binary Search Trees | [Link](/Medium/BST Construction) |
| 36. | Validate BST | 🟦 | Binary Search Trees | [Link](/Medium/Validate BST) |
| 37. | BST Traversal | 🟦 | Binary Search Trees | [Link](/Medium/BST Traversal) |
| 38. | Min Height BST | 🟦 | Binary Search Trees | [Link](/Medium/Min Height BST) |
| 39. | Find Kth Largest Value In BST | 🟦 | Binary Search Trees | [Link](/Medium/Find Kth Largest Value In BST) |
| 40. | Reconstruct BST | 🟦 | Binary Search Trees | [Link](/Medium/Reconstruct BST) |
| 41. | Same BSTs | 🟥 | Binary Search Trees | [Link](/Hard/Same BSTs) |
| 42. | Validate Three Nodes | 🟥 | Binary Search Trees | [Link](/Hard/Validate Three Nodes) |
| 43. | Repair BST | 🟥 | Binary Search Trees | [Link](/Hard/Repair BST) |
| 44. | Right Smaller Than | ⬛ | Binary Search Trees | [Link](/Very Hard/Right Smaller Than) |
| 45. | Branch Sums | 🟩 | Binary Trees | [Link](/Easy/Branch Sums) |
| 46. | Node Depths | 🟩 | Binary Trees | [Link](/Easy/Node Depths) |
| 47. | Evaluate Expression Tree | 🟩 | Binary Trees | [Link](/Easy/Evaluate Expression Tree) |
| 48. | Invert Binary Tree | 🟦 | Binary Trees | [Link](/Medium/Invert Binary Tree) |
| 49. | Binary Tree Diameter | 🟦 | Binary Trees | [Link](/Medium/Binary Tree Diameter) |
| 50. | Find Successor | 🟦 | Binary Trees | [Link](/Medium/Find Successor) |
| 51. | Height Balanced Binary Tree | 🟦 | Binary Trees | [Link](/Medium/Height Balanced Binary Tree) |
| 52. | Merge Binary Trees | 🟦 | Binary Trees | [Link](/Medium/Merge Binary Trees) |
| 53. | Symmetrical Tree | 🟦 | Binary Trees | [Link](/Medium/Symmetrical Tree) |
| 54. | Split Binary Tree | 🟦 | Binary Trees | [Link](/Medium/Split Binary Tree) |
| 55. | Max Path Sum In Binary Tree | 🟥 | Binary Trees | [Link](/Hard/Max Path Sum In Binary Tree) |
| 56. | Find Nodes Distance K | 🟥 | Binary Trees | [Link](/Hard/Find Nodes Distance K) |
| 57. | Iterative In-order Traversal | ⬛ | Binary Trees | [Link](/Very Hard/Iterative In-order Traversal) |
| 58. | Flatten Binary Tree | ⬛ | Binary Trees | [Link](/Very Hard/Flatten Binary Tree) |
| 59. | Right Sibling Tree | ⬛ | Binary Trees | [Link](/Very Hard/Right Sibling Tree) |
| 60. | All Kinds Of Node Depths | ⬛ | Binary Trees | [Link](/Very Hard/All Kinds Of Node Depths) |
| 61. | Compare Leaf Traversal | ⬛ | Binary Trees | [Link](/Very Hard/Compare Leaf Traversal) |
| 62. | Max Subset Sum No Adjacent | 🟦 | Dynamic Programming | [Link](/Medium/Max Subset Sum No Adjacent) |
| 63. | Number Of Ways To Make Change | 🟦 | Dynamic Programming | [Link](/Medium/Number Of Ways To Make Change) |
| 64. | Min Number Of Coins For Change | 🟦 | Dynamic Programming | [Link](/Medium/Min Number Of Coins For Change) |
| 65. | Levenshtein Distance | 🟦 | Dynamic Programming | [Link](/Medium/Levenshtein Distance) |
| 66. | Number Of Ways To Traverse Graph | 🟦 | Dynamic Programming | [Link](/Medium/Number Of Ways To Traverse Graph) |
| 67. | Max Sum Increasing Subsequence | 🟥 | Dynamic Programming | [Link](/Hard/Max Sum Increasing Subsequence) |
| 68. | Longest Common Subsequence | 🟥 | Dynamic Programming | [Link](/Hard/Longest Common Subsequence) |
| 69. | Min Number Of Jumps | 🟥 | Dynamic Programming | [Link](/Hard/Min Number Of Jumps) |
| 70. | Water Area | 🟥 | Dynamic Programming | [Link](/Hard/Water Area) |
| 71. | Knapsack Problem | 🟥 | Dynamic Programming | [Link](/Hard/Knapsack Problem) |
| 72. | Disk Stacking | 🟥 | Dynamic Programming | [Link](/Hard/Disk Stacking) |
| 73. | Numbers In Pi | 🟥 | Dynamic Programming | [Link](/Hard/Numbers In Pi) |
| 74. | Maximum Sum Submatrix | 🟥 | Dynamic Programming | [Link](/Hard/Maximum Sum Submatrix) |
| 75. | Maximize Expression | 🟥 | Dynamic Programming | [Link](/Hard/Maximize Expression) |
| 76. | Dice Throws | 🟥 | Dynamic Programming | [Link](/Hard/Dice Throws) |
| 77. | Juice Bottling | 🟥 | Dynamic Programming | [Link](/Hard/Juice Bottling) |
| 78. | Max Profit With K Transactions | ⬛ | Dynamic Programming | [Link](/Very Hard/Max Profit With K Transactions) |
| 79. | Palindrome Partitioning Min Cuts | ⬛ | Dynamic Programming | [Link](/Very Hard/Palindrome Partitioning Min Cuts) |
| 80. | Longest Increasing Subsequence | ⬛ | Dynamic Programming | [Link](/Very Hard/Longest Increasing Subsequence) |
| 81. | Longest String Chain | ⬛ | Dynamic Programming | [Link](/Very Hard/Longest String Chain) |
| 82. | Square of Zeroes | ⬛ | Dynamic Programming | [Link](/Very Hard/Square of Zeroes) |
| 83. | Kadane's Algorithm | 🟦 | Famous Algorithms | [Link](/Medium/Kadane's Algorithm) |
| 84. | Stable internships | 🟦 | Famous Algorithms | [Link](/Medium/Stable internships) |
| 85. | Union Find | 🟦 | Famous Algorithms | [Link](/Medium/Union Find) |
| 86. | Dijkstra's Algorithm | 🟥 | Famous Algorithms | [Link](/Hard/Dijkstra's Algorithm) |
| 87. | Topological Sort | 🟥 | Famous Algorithms | [Link](/Hard/Topological Sort) |
| 88. | Kruskal's Algorithm | 🟥 | Famous Algorithms | [Link](/Hard/Kruskal's Algorithm) |
| 89. | Knuth—Morris—Pratt Algorithm | ⬛ | Famous Algorithms | [Link](/Very Hard/Knuth—Morris—Pratt Algorithm) |
| 90. | A* Algorithm | ⬛ | Famous Algorithms | [Link](/Very Hard/A* Algorithm) |
| 91. | Depth-first Search | 🟩 | Graphs | [Link](/Easy/Depth-first Search) |
| 92. | Single Cycle Check | 🟦 | Graphs | [Link](/Medium/Single Cycle Check) |
| 93. | Breadth-first Search | 🟦 | Graphs | [Link](/Medium/Breadth-first Search) |
| 94. | River Sizes | 🟦 | Graphs | [Link](/Medium/River Sizes) |
| 95. | Youngest Common Ancestor | 🟦 | Graphs | [Link](/Medium/Youngest Common Ancestor) |
| 96. | Remove Islands | 🟦 | Graphs | [Link](/Medium/Remove Islands) |
| 97. | Cycle In Graph | 🟦 | Graphs | [Link](/Medium/Cycle In Graph) |
| 98. | Minimum Passes Of Matrix | 🟦 | Graphs | [Link](/Medium/Minimum Passes Of Matrix) |
| 99. | Two-Colorable | 🟦 | Graphs | Link |
| 100. | Boggle Board | 🟥 | Graphs | [Link](/Hard/Boggle Board) |
| 101. | Largest Island | 🟥 | Graphs | [Link](/Hard/Largest Island) |
| 102. | Rectangle Mania | ⬛ | Graphs | [Link](/Very Hard/Rectangle Mania) |
| 103. | Detect Arbitrage | ⬛ | Graphs | [Link](/Very Hard/Detect Arbitrage) |
| 104. | Two-Edge-Connected Graph | ⬛ | Graphs | [Link](/Very Hard/Two-Edge-Connected Graph) |
| 105. | Airport Connections | ⬛ | Graphs | [Link](/Very Hard/Airport Connections) |
| 106. | Minimum Waiting Time | 🟩 | Greedy Algorithms | [Link](/Easy/Minimum Waiting Time) |
| 107. | Class Photos | 🟩 | Greedy Algorithms | [Link](/Easy/Class Photos) |
| 108. | Tandem Bicycle | 🟩 | Greedy Algorithms | [Link](/Easy/Tandem Bicycle) |
| 109. | Optimal Freelancing | 🟩 | Greedy Algorithms | [Link](/Easy/Optimal Freelancing) |
| 110. | Task Assignment | 🟦 | Greedy Algorithms | [Link](/Medium/Task Assignment) |
| 111. | Valid Starting City | 🟦 | Greedy Algorithms | [Link](/Medium/Valid Starting City) |
| 112. | Min Heap Construction | 🟦 | Heaps | [Link](/Medium/Min Heap Construction) |
| 113. | Continuous Median | 🟥 | Heaps | [Link](/Hard/Continuous Median) |
| 114. | Sort K-Sorted Array | 🟥 | Heaps | [Link](/Hard/Sort K-Sorted Array) |
| 115. | Laptop Rentals | 🟥 | Heaps | [Link](/Hard/Laptop Rentals) |
| 116. | Merge Sorted Arrays | ⬛ | Heaps | [Link](/Very Hard/Merge Sorted Arrays) |
| 117. | Remove Duplicates From Linked List | 🟩 | Linked Lists | [Link](/Easy/Remove Duplicates From Linked List) |
| 118. | Middle Node | 🟩 | Linked Lists | [Link](/Easy/Middle Node) |
| 119. | Linked List Construction | 🟦 | Linked Lists | [Link](/Medium/Linked List Construction) |
| 120. | Remove Kth Node From End | 🟦 | Linked Lists | [Link](/Medium/Remove Kth Node From End) |
| 121. | Sum of Linked Lists | 🟦 | Linked Lists | [Link](/Medium/Sum of Linked Lists) |
| 122. | Merging Linked Lists | 🟦 | Linked Lists | [Link](/Medium/Merging Linked Lists) |
| 123. | Find Loop | 🟥 | Linked Lists | [Link](/Hard/Find Loop) |
| 124. | Reverse Linked List | 🟥 | Linked Lists | [Link](/Hard/Reverse Linked List) |
| 125. | Merge Linked Lists | 🟥 | Linked Lists | [Link](/Hard/Merge Linked Lists) |
| 126. | Shift Linked List | 🟥 | Linked Lists | [Link](/Hard/Shift Linked List) |
| 127. | LRU Cache | ⬛ | Linked Lists | [Link](/Very Hard/LRU Cache) |
| 128. | Rearrange Linked List | ⬛ | Linked Lists | [Link](/Very Hard/Rearrange Linked List) |
| 129. | Linked List Palindrome | ⬛ | Linked Lists | [Link](/Very Hard/Linked List Palindrome) |
| 130. | Zip Linked List | ⬛ | Linked Lists | [Link](/Very Hard/Zip Linked List) |
| 131. | Node Swap | ⬛ | Linked Lists | [Link](/Very Hard/Node Swap) |
| 132. | Nth Fibonacci | 🟩 | Recursion | [Link](/Easy/Nth Fibonacci) |
| 133. | Product Sum | 🟩 | Recursion | [Link](/Easy/Product Sum) |
| 134. | Permutations | 🟦 | Recursion | Link |
| 135. | Powerset | 🟦 | Recursion | Link |
| 136. | Phone Number Mnemonics | 🟦 | Recursion | [Link](/Medium/Phone Number Mnemonics) |
| 137. | Staircase Traversal | 🟦 | Recursion | [Link](/Medium/Staircase Traversal) |
| 138. | Blackjack Probability | 🟦 | Recursion | [Link](/Medium/Blackjack Probability) |
| 139. | Reveal Minesweeper | 🟦 | Recursion | [Link](/Medium/Reveal Minesweeper) |
| 140. | Lowest Common Manager | 🟥 | Recursion | [Link](/Hard/Lowest Common Manager) |
| 141. | Interweaving Strings | 🟥 | Recursion | [Link](/Hard/Interweaving Strings) |
| 142. | Solve Sudoku | 🟥 | Recursion | [Link](/Hard/Solve Sudoku) |
| 143. | Generate Div Tags | 🟥 | Recursion | [Link](/Hard/Generate Div Tags) |
| 144. | Ambiguous Measurements | 🟥 | Recursion | [Link](/Hard/Ambiguous Measurements) |
| 145. | Number Of Binary Tree Topologies | ⬛ | Recursion | [Link](/Very Hard/Number Of Binary Tree Topologies) |
| 146. | Non-Attacking Queens | ⬛ | Recursion | [Link](/Very Hard/Non-Attacking Queens) |
| 147. | Binary Search | 🟩 | Searching | [Link](/Easy/Binary Search) |
| 148. | Find Three Largest Numbers | 🟩 | Searching | [Link](/Easy/Find Three Largest Numbers) |
| 149. | Search In Sorted Matrix | 🟦 | Searching | [Link](/Medium/Search In Sorted Matrix) |
| 150. | Shifted Binary Search | 🟥 | Searching | [Link](/Hard/Shifted Binary Search) |
| 151. | Search For Range | 🟥 | Searching | [Link](/Hard/Search For Range) |
| 152. | Quickselect | 🟥 | Searching | Link |
| 153. | Index Equals Value | 🟥 | Searching | [Link](/Hard/Index Equals Value) |
| 154. | Median Of Two Sorted Arrays | ⬛ | Searching | [Link](/Very Hard/Median Of Two Sorted Arrays) |
| 155. | Optimal Assembly Line | ⬛ | Searching | [Link](/Very Hard/Optimal Assembly Line) |
| 156. | Bubble Sort | 🟩 | Sorting | [Link](/Easy/Bubble Sort) |
| 157. | Insertion Sort | 🟩 | Sorting | [Link](/Easy/Insertion Sort) |
| 158. | Selection Sort | 🟩 | Sorting | [Link](/Easy/Selection Sort) |
| 159. | Three Number Sort | 🟦 | Sorting | [Link](/Medium/Three Number Sort) |
| 160. | Quick Sort | 🟥 | Sorting | [Link](/Hard/Quick Sort) |
| 161. | Heap Sort | 🟥 | Sorting | [Link](/Hard/Heap Sort) |
| 162. | Radix Sort | 🟥 | Sorting | [Link](/Hard/Radix Sort) |
| 163. | Merge Sort | ⬛ | Sorting | [Link](/Very Hard/Merge Sort) |
| 164. | Count Inversions | ⬛ | Sorting | [Link](/Very Hard/Count Inversions) |
| 165. | Min Max Stack Construction | 🟦 | Stacks | [Link](/Medium/Min Max Stack Construction) |
| 166. | Balanced Brackets | 🟦 | Stacks | [Link](/Medium/Balanced Brackets) |
| 167. | Sunset Views | 🟦 | Stacks | [Link](/Medium/Sunset Views) |
| 168. | Best Digits | 🟦 | Stacks | [Link](/Medium/Best Digits) |
| 169. | Sort Stack | 🟦 | Stacks | [Link](/Medium/Sort Stack) |
| 170. | Next Greater Element | 🟦 | Stacks | [Link](/Medium/Next Greater Element) |
| 171. | Reverse Polish Notation | 🟦 | Stacks | [Link](/Medium/Reverse Polish Notation) |
| 172. | Colliding Asteroids | 🟦 | Stacks | [Link](/Medium/Colliding Asteroids) |
| 173. | Shorten Path | 🟥 | Stacks | [Link](/Hard/Shorten Path) |
| 174. | Largest Rectangle Under Skyline | 🟥 | Stacks | [Link](/Hard/Largest Rectangle Under Skyline) |
| 175. | Largest Park | ⬛ | Stacks | [Link](/Very Hard/Largest Park) |
| 176. | Palindrome Check | 🟩 | Strings | [Link](/Easy/Palindrome Check) |
| 177. | Caesar Cipher Encryptor | 🟩 | Strings | [Link](/Easy/Caesar Cipher Encryptor) |
| 178. | Run-Length Encoding | 🟩 | Strings | [Link](/Easy/Run-Length Encoding) |
| 179. | Common Characters | 🟩 | Strings | [Link](/Easy/Common Characters) |
| 180. | Generate Document | 🟩 | Strings | [Link](/Easy/Generate Document) |
| 181. | First Non-Repeating Character | 🟩 | Strings | [Link](/Easy/First Non-Repeating Character) |
| 182. | Semordnilap | 🟩 | Strings | Link |
| 183. | Longest Palindromic Substring | 🟦 | Strings | [Link](/Medium/Longest Palindromic Substring) |
| 184. | Group Anagrams | 🟦 | Strings | [Link](/Medium/Group Anagrams) |
| 185. | Valid IP Addresses | 🟦 | Strings | [Link](/Medium/Valid IP Addresses) |
| 186. | Reverse Words In String | 🟦 | Strings | [Link](/Medium/Reverse Words In String) |
| 187. | Minimum Characters For Words | 🟦 | Strings | [Link](/Medium/Minimum Characters For Words) |
| 188. | One Edit | 🟦 | Strings | [Link](/Medium/One Edit) |
| 189. | Longest Substring Without Duplication | 🟥 | Strings | [Link](/Hard/Longest Substring Without Duplication) |
| 190. | Underscorify Substring | 🟥 | Strings | [Link](/Hard/Underscorify Substring) |
| 191. | Pattern Matcher | 🟥 | Strings | [Link](/Hard/Pattern Matcher) |
| 192. | Smallest Substring Containing | ⬛ | Strings | [Link](/Very Hard/Smallest Substring Containing) |
| 193. | Longest Balanced Substring | ⬛ | Strings | [Link](/Very Hard/Longest Balanced Substring) |
| 194. | Suffix Trie Construction | 🟦 | Tries | [Link](/Medium/Suffix Trie Construction) |
| 195. | Multi String Search | 🟥 | Tries | [Link](/Hard/Multi String Search) |