/keetcoder

Your structured roadmap to mastering data structures & algorithms for LeetCode 🔥 . 150+ classic problems, clean code in C++/Java/Python/Go/JavaScript, detailed explanations, mind maps, and visual guides to help you learn deeply and efficiently.

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keetcoder

Your structured roadmap to mastering data structures & algorithms for LeetCode 🔥 . 150+ classic problems, clean code in C++/Java/Python/Go/JavaScript, detailed explanations, mind maps, and visual guides to help you learn deeply and efficiently.

Array

  1. Introduction to Arrays
  2. 704.Binary Search
  3. 27.Remove Element
  4. 977.Squares of a Sorted Array
  5. 209.Minimum Size Subarray Sum
  6. 59.Spiral Matrix II
  7. Array Summary

Linked List

  1. Linked List Basics
  2. 203.Remove Linked List Elements
  3. 707.Design Linked List
  4. 206.Reverse Linked List
  5. 24.Swap Nodes In Pairs
  6. 19.Remove Nth Node From End Of List
  7. 160.Intersection Of Two Linked Lists
  8. 142.Linked List Cycle II
  9. Linked List Summary

Hash Table

  1. Introduction to Hash Table
  2. 242.Valid Anagram
  3. 349.Intersection of Two Arrays
  4. 202.Happy Number
  5. 1.Two Sum
  6. 454.4Sum II
  7. 383.Ransom Note
  8. 15.3Sum
  9. 18.4Sum
  10. Hash Table Summary

String

  1. 344.Reverse String
  2. 541.Reverse String II
  3. 151.Reverse Words in a String
  4. 28.Implement strStr()
  5. 459.Repeated Substring Pattern
  6. String Summary

Double Pointers

  1. 27.Remove Element
  2. 344.Reverse String
  3. 151.Reverse Words in a String
  4. 206.Reverse Linked List
  5. 19.Remove Nth Node From End of List
  6. 160.Intersection of Two Linked Lists
  7. 142.Linked List Cycle II
  8. 15.3Sum
  9. 18.4Sum
  10. Double Pointers Summary

Stack and Queue

  1. Introduction to Stack and Queue
  2. 232.Implement Queue using Stacks
  3. 225.Implement Stack using Queues
  4. 20.Valid Parentheses
  5. 1047.Remove All Adjacent Duplicates in String
  6. 150.Evaluate Reverse Polish Notation
  7. 239.Sliding Window Maximum
  8. 347.Top K Frequent Elements
  9. Stack and Queue Summary

Binary Tree

  1. Introduction to Binary Trees
  2. Recursive Traversal of Binary Trees
  3. Iterative Traversal of Binary Trees
  4. Unified Iterative Method for Binary Trees
  5. 102.Binary Tree Level Order Traversal
  6. 226.Invert Binary Tree
  7. 101.Symmetric Tree
  8. 104.Maximum Depth of Binary Tree
  9. 111.Minimum Depth of Binary Tree
  10. 222.Count Complete Tree Nodes
  11. 110.Balanced Binary Tree
  12. 257.Binary Tree Paths
  13. 404.Sum of Left Leaves
  14. 513.Find Bottom Left Tree Value
  15. 112.Path Sum
  16. 106.Construct Binary Tree from Inorder and Postorder Traversal
  17. 654.Maximum Binary Tree
  18. 617.Merge Two Binary Trees
  19. 700.Search in a Binary Search Tree
  20. 98.Validate Binary Search Tree
  21. 530.Minimum Absolute Difference in BST
  22. 501.Find Mode in Binary Search Tree
  23. 236.Lowest Common Ancestor of a Binary Tree
  24. 235.Lowest Common Ancestor of a BST
  25. 701.Insert into a Binary Search Tree
  26. 450.Delete Node in a BST
  27. 669.Trim a Binary Search Tree
  28. 108.Convert Sorted Array to BST
  29. 538.Convert BST to Greater Tree
  30. Binary Tree Summary

Backtracking

  1. Introduction to Backtracking
  2. 77.Combinations
  3. 77.Combinations (Optimized)
  4. 216.Combination Sum III
  5. 17.Letter Combinations of a Phone Number
  6. 39.Combination Sum
  7. 40.Combination Sum II
  8. 131.Palindrome Partitioning
  9. 93.Restore IP Addresses
  10. 78.Subsets
  11. 90.Subsets II
  12. 491.Increasing Subsequences
  13. 46.Permutations
  14. 47.Permutations II
  15. Alternative Deduplication in Backtracking
  16. 332.Reconstruct Itinerary
  17. 51.N-Queens
  18. 37.Sudoku Solver
  19. Backtracking Summary

Greedy Algorithm

  1. Introduction to Greedy Algorithm
  2. 455.Assign Cookies
  3. 376.Wiggle Subsequence
  4. 53.Maximum Subarray
  5. 122.Best Time to Buy and Sell Stock II
  6. 55.Jump Game
  7. 45.Jump Game II
  8. 1005.Maximize Sum After K Negations
  9. 134.Gas Station
  10. 135.Candy
  11. 860.Lemonade Change
  12. 406.Queue Reconstruction by Height
  13. Queue Reconstruction by Height (Vector Explanation)
  14. 452.Minimum Number of Arrows to Burst Balloons
  15. 435.Non-overlapping Intervals
  16. 763.Partition Labels
  17. 56.Merge Intervals
  18. 738.Monotone Increasing Digits
  19. 968.Binary Tree Cameras
  20. Greedy Algorithms Summary

Dynamic Programming

  1. Introduction to Dynamic Programming
  2. 509.Fibonacci Number
  3. 70.Climbing Stairs
  4. 746.Min Cost Climbing Stairs
  5. 62.Unique Paths
  6. 63.Unique Paths II
  7. 343.Integer Break
  8. 96.Unique Binary Search Trees
  9. 0-1 Knapsack Theory (Part 1)
  10. 0-1 Knapsack Theory (Part 2)
  11. 416.Partition Equal Subset Sum
  12. 1049.Last Stone Weight II
  13. 494.Target Sum
  14. 474.Ones and Zeroes
  15. Complete Knapsack Theory
  16. 518.Coin Change II
  17. 377.Combination Sum IV
  18. Climbing Stairs (Advanced)
  19. 322.Coin Change
  20. 279.Perfect Squares
  21. 139.Word Break
  22. Multiple Knapsack Theory
  23. Knapsack Summary
  24. 198.House Robber
  25. 213.House Robber II
  26. 337.House Robber III
  27. 121.Best Time to Buy and Sell Stock
  28. 122.Best Time to Buy and Sell Stock II (DP)
  29. 123.Best Time to Buy and Sell Stock III
  30. 188.Best Time to Buy and Sell Stock IV
  31. 309.Best Time to Buy and Sell Stock with Cooldown
  32. 714.Best Time to Buy and Sell Stock with Transaction Fee
  33. Stock Problems Summary
  34. 300.Longest Increasing Subsequence
  35. 674.Longest Continuous Increasing Subsequence
  36. 718.Maximum Length of Repeated Subarray
  37. 1143.Longest Common Subsequence
  38. 1035.Uncrossed Lines
  39. 53.Maximum Subarray (DP)
  40. 392.Is Subsequence
  41. 115.Distinct Subsequences
  42. 583.Delete Operation for Two Strings
  43. 72.Edit Distance
  44. Edit Distance Summary
  45. 647.Palindromic Substrings
  46. 516.Longest Palindromic Subsequence
  47. Dynamic Programming Summary

Monotonic Stack

  1. 739.Daily Temperatures
  2. 496.Next Greater Element I
  3. 503.Next Greater Element II
  4. 42.Trapping Rain Water
  5. 84.Largest Rectangle in Histogram