in this repository , I am try to practice and enhance my problem solving and coding skills by using kotlin . this repository contains three major folders [easy - medium - hard] based on problem level, you can find the problem in every folder by problem name and number.

• Easy
• Medium
• Hard
  

• 303. Range Sum Query - Immutable
• 1920. Build Array from Permutation
• 1913. Maximum Product Difference Between Two Pairs
• 653. Two Sum IV - Input is a BST
• 598. Range Addition II
• 543. Diameter of Binary Tree
• 155. Min Stack
• 226. Invert Binary Tree
• 404. Sum of Left Leaves
• 441. Arranging Coins
• 448. Find All Numbers Disappeared in an Array
• 461. Hamming Distance
• 35. Search Insert Position
• 941. Valid Mountain Array -Leetcode Link
• 1672. Richest Customer Wealth -Leetcode Link
• 121. Best Time to Buy and Sell Stock -Leetcode Link
• 389. Find the Difference -Leetcode Link
• 258. Add Digits -Leetcode Link
• 104. Maximum Depth of Binary Tree -Leetcode Link
• 136. Single Number -Leetcode Link
• 171. Excel Sheet Column Number -Leetcode Link
• 169. Majority Element -Leetcode Link
• 228. Summary Ranges -Leetcode Link
• 338. Counting Bits -Leetcode Link
• 392. Is Subsequence -Leetcode Link
• 21. Merge Two Sorted Lists -Leetcode Link
• 141. Linked List Cycle -Leetcode Link
• 20. Valid Parentheses -Leetcode Link
• 94. Binary Tree Inorder Traversal -Leetcode Link
• 344. Reverse String -Leetcode Link
• 1721. Swapping Nodes in a Linked List -Leetcode Link
• 703. Kth Largest Element in a Stream -Leetcode Link
• 682. Baseball Game -Leetcode Link
• 700. Search in a Binary Search Tree -Leetcode Link
• 905. Sort Array By Parity -Leetcode Link
• 867. Transpose Matrix -Leetcode Link
• 88. Merge Sorted Array -Leetcode Link
• 1332. Remove Palindromic Subsequences -Leetcode Link
• 283. Move Zeroes -Leetcode Link
• 367. Valid Perfect Square -Leetcode Link
• 191. Number of 1 Bits -Leetcode Link
• 231. Power of Two -Leetcode Link
• 268. Missing Number -Leetcode Link
• 2220. Minimum Bit Flips to Convert Number -Leetcode Link
• 13. Roman to Integer -Leetcode Link
• 1089. Duplicate Zeros -Leetcode Link
• 1832. Check if the Sentence Is Pangram -Leetcode Link
• 1662. Check If Two String Arrays are Equivalent -Leetcode Link
• 345. Reverse Vowels of a String -Leetcode Link
• 1323. Maximum 69 Number -Leetcode Link
• 1544. Make The String Great -Leetcode Link
• 374. Guess Number Higher or Lower -Leetcode Link
• 26. Remove Duplicates from Sorted Array -Leetcode Link
• 263. Ugly Number -Leetcode Link
• 111. Minimum Depth of Binary Tree -Leetcode Link
• 144. Binary Tree Preorder Traversal -Leetcode Link
• 145. Binary Tree Postorder Traversal -Leetcode Link
• 1207. Unique Number of Occurrences -Leetcode Link
• 1704. Determine if String Halves Are Alike -Leetcode Link
• 1945. Sum of Digits of String After Convert - leetcode link String Simulation
• 1684. Count the Number of Consistent Strings - leetcode link String Simulation Array Counting
• 1331. Rank Transform of an Array - leetcode link Array Hash Table Sorting
• 2696. Minimum String Length After Removing Substrings - leetcode link String Stack Simulation
• 1455. Check If a Word Occurs As a Prefix of Any Word in a Sentence - leetcode link String Two Pointer String Matching
• 2558. Take Gifts From the Richest Pile - leetcode link Array Simulation
• 3264. Final Array State After K Multiplication Operations I - leetcode link Array Simulation
• 1971. Find if Path Exists in Graph - leetcode link Graph DFS
• 1790. Check if One String Swap Can Make Strings Equal - leetcode link Hash map Array Counting
• 1941. Check if All Characters Have Equal Number of Occurrences - leetcode link Hash map Array Counting
• 1995. Count Special Quadruplets - leetcode link Hash map Array Counting
• 2032. Two Out of Three - leetcode link Hash map Array Counting
• 1550. Three Consecutive Odds - leetcode link Array
• 1475. Final Prices With a Special Discount in a Shop - leetcode link Array Stack
• 1974. Minimum Time to Type Word Using Special Typewriter - leetcode link Array Stack
• 3024. Type of Triangle - leetcode link Array Stack
  

• 1448. Count Good Nodes in Binary Tree
• 91. Decode Ways
• 633. Sum of Square Numbers
• 153. Find Minimum in Rotated Sorted Array
• 437. Path Sum III
• 151. Reverse Words in a String
• 75. Sort Colors
• 130. Surrounded Regions
• 260. Single Number III
• 43. Multiply Strings
• 96. Unique Binary Search Trees
• 122. Best Time to Buy and Sell Stock II
• 62. Unique Paths
• 450. Delete Node in a BST
• 1305. All Elements in Two Binary Search Trees-Leetcode Link
• 189. Rotate Array-Leetcode Link
• 454. 4Sum II-Leetcode Link
• 525. Contiguous Array-Leetcode Link
• 80. Remove Duplicates from Sorted Array II-Leetcode Link
• 532. K-diff Pairs in an Array-Leetcode Link
• 560. Subarray Sum Equals K-Leetcode Link
• 39. Combination Sum-Leetcode Link
• 402. Remove K Digits-Leetcode Link
• 1288. Remove Covered Intervals-Leetcode Link
• 148. Sort List-Leetcode Link
• 165. Compare Version Numbers-Leetcode Link
• 662. Maximum Width of Binary Tree-Leetcode Link
• 413. Arithmetic Slices-Leetcode Link
• 799. Champagne Tower-Leetcode Link
• 740. Delete and Earn-Leetcode Link
• 2. Add Two Number-Leetcode Link
• 71. Simplify Path-Leetcode Link
  
• 946. Validate Stack Sequences-Leetcode Link
  
• 1249. Minimum Remove to Make Valid Parentheses-Leetcode Link
  
• 856. Score of Parentheses-Leetcode Link
  
• 316. Remove Duplicate Letters-Leetcode Link
  
• 1007. Minimum Domino Rotations For Equal Row-Leetcode Link
  
• 74. Search a 2D Matrix-Leetcode Link
  
• 347. Top K Frequent Elements-Leetcode Link
  
• 289. Game of Life-Leetcode Link
  
• 3. Longest Substring Without Repeating Characters-Leetcode Link
  
• 167. Two Sum II - Input Array Is Sorted -Leetcode Link
• 5. Longest Palindromic Substring -Leetcode Link
• 820. Short Encoding of Words -Leetcode Link
• 215. Kth Largest Element inin an Array -Leetcode Link
• 1689. Partitioning Into Minimum Number Of Deci-Binary Numbers -Leetcode Link
• 199. Binary Tree Right Side View -Leetcode Link
• 473. Matchsticks to Square -Leetcode Link
• 102. Binary Tree Level Order Traversal -Leetcode Link
• 114. Flatten Binary Tree to Linked List -Leetcode Link
• 890. Find and Replace Pattern -Leetcode Link
• 729. My Calendar I -Leetcode Link
• 98. Validate Binary Search Tree -Leetcode Link
• 1318. Minimum Flips to Make a OR b Equal to c -Leetcode Link
• 237. Delete Node in a Linked List -Leetcode Link
• 38. Count and Say -Leetcode Link
• 692. Top K Frequent Words -Leetcode Link
• 12. Integer to Roman -Leetcode Link
• 1239. Maximum Length of a Concatenated String with Unique Characters -Leetcode Link
• 523. Continuous Subarray Sum -Leetcode Link
• 49. Group Anagrams -Leetcode Link
• 1706. Where Will the Ball Fall -Leetcode Link
• 433. Minimum Genetic Mutation -Leetcode Link
• 2131. Longest Palindrome by Concatenating Two Letter Words -Leetcode Link
• 901. Online Stock Span -Leetcode Link
• 222. Count Complete Tree Nodes -Leetcode Link
• 223. Rectangle Area -Leetcode Link
• 1926. Nearest Exit from Entrance in Maze -Leetcode Link
• 79. Word Search -Leetcode Link
• 2225. Find Players With Zero or One Losses -Leetcode Link
• 926. Flip String to Monotone Increasing -Leetcode Link
• 1905. Count Sub Islands- Leetcode Link BFS
• 947. Most Stones Removed with Same Row or Column- Leetcode Link Graph DFS BFS
• 1894. Find the Student that Will Replace the Chalk - Leetcode link Prefix Sum
• 874. Walking Robot Simulation - Leetcode link Array Hash Table Simulation
• 3217. Delete Nodes From Linked List Present in Array - Leetcode link Array Hash Table Linked List
• 2326. Spiral Matrix IV - Leetcode link Array Hash Table Linked List
• 2707. Extra Characters in a String - Leetcode link Array Hash Table Dynamic Programming Recurrsion
• 3043. Find the Length of the Longest Common Prefix - Leetcode link Array Hash Table String Trie
• 731. My Calendar II - Leetcode link Array Binary search Design Segment Tree Prefix Sum Ordered Set
• 1497. Check If Array Pairs Are Divisible by k - Leetcode link Array Hash Table Counting
• 2491. Divide Players Into Teams of Equal Skill - Leetcode link Array Hash Table Sorting Two Pointers
• 1963. Minimum Number of Swaps to Make the String Balanced - Leetcode link Stack String Two Pointers
• 921. Minimum Add to Make Parentheses Valid - Leetcode link Stack String Two Pointers
• 1942. The Number of the Smallest Unoccupied Chair - Leetcode link Array Hash Table Heap(Priority Queue)
• 1593. Split a String Into the Max Number of Unique Substrings - Leetcode link Array Hash Table Heap(Priority Queue)
• 2583. Kth Largest Sum in a Binary Tree - Leetcode link Tree BFS Sorting Binary Tree
• 951.Flip Equivalent Binary Trees - Leetcode link Tree DFS Binary Tree
• 1233. Remove Sub-Folders from the Filesystem - Leetcode link String Array Sorting
• 2501. Longest Square Streak in an Array - Leetcode link Hash Table Array Sorting Binary Search
• 2684. Maximum Number of Moves in a Grid - Leetcode link Hash Table Array Sorting Binary Search
• 2275. Largest Combination With Bitwise AND Greater Than Zero - Leetcode link Hash Table Array Bit Manipulation Counting
• 2337. Move Pieces to Obtain a String - Leetcode link Hash Table Array Bit Manipulation Counting
• 2554. Maximum Number of Integers to Choose From a Range I - Leetcode link Hash Table Array Binary Search Greedy
• 2593. Find Score of an Array After Marking All Elements - Leetcode link Hash Table Array Sorting Heap(Priority Queue
• 2425. Bitwise XOR of All Pairings - Leetcode link Hash Table Bit Manipulation
• 2683. Neighboring Bitwise XOR - Leetcode link Array Bit Manipulation
• 2661. First Completely Painted Row or Column - Leetcode link Array Bit Manipulation
• 2017. Grid Game - Leetcode link Array Prefix Sum
• 802. Find Eventual Safe States - Leetcode link Array Prefix Sum
• 1462. Course Schedule IV - Leetcode link Graph DFS BFS
• 2658. Maximum Number of Fish in a Grid - Leetcode link Graph DFS BFS
• 684. Redundant Connection - Leetcode link Graph DFS BFS
• 2342. Max Sum of a Pair With Equal Sum of Digits - Leetcode link Hash Table Array
• 3066. Minimum Operations to Exceed Threshold Value II - Leetcode link Priority Queue Array Simulation
• 2698. Find the Punishment Number of an Integer - Leetcode link Priority Queue Array Simulation
• 1718. Construct the Lexicographically Largest Valid Sequence - Leetcode link Backtracking Array
• 1524. Number of Sub-arrays With Odd Sum - Leetcode link Prefix Sum Array
• 1749. Maximum Absolute Sum of Any Subarray - Leetcode link Prefix Sum Array
• 3191. Minimum Operations to Make Binary Array Elements Equal to One I - Leetcode link Bit Manipulation Prefix Sum Array
• 2115. Find All Possible Recipes from Given Supplies - Leetcode link Array BFS DFS Hash Set
• 3169. Count Days Without Meetings - Leetcode link Array BFS DFS Hash Set
• 2033. Minimum Operations to Make a Uni-Value Grid - Leetcode link Array Math Sorting Matrix
• 1123. Lowest Common Ancestor of Deepest Leaves - Leetcode link Array Sliding Window
• 2799. Count Complete Subarrays in an Array - Leetcode link Array Math Sorting Matrix
• 2962. Count Subarrays Where Max Element Appears at Least K Times - Leetcode link Array Math Sorting Matrix
• 3355. Zero Array Transformation I - Leetcode link Array prefix sum

• 76. Minimum Window Substring
• 2290. Minimum Obstacle Removal to Reach Corner Leetcode link Array Breadth-First-Search Graph Heap(Priority Queue) Matrix Shortest Path
• 2493. Divide Nodes Into the Maximum Number of Groups Leetcode link Array Breadth-First-Search Graph Heap(Priority Queue) Matrix Shortest Path
  • 2503. Maximum Number of Points From Grid Queries - Leetcode link DFS BFS Tree Hash Table