Athena Algorithms

Athena Algorithms is a collection of algorithm solutions.
These algorithm solutions are licensed under CC-BY-SA 4.0.

Latest: 57. Valid Palindrome [Java, Python]

Table of Contents

• Algorithm Problems
  • Array
    • Standard
      • 1. Array Partition [Java, Python, C++, Golang]
      • 31. Minimum Number Game [Java]
    • Meaningful Index (Automatic Sorting)
      • 34. Sort Array by Increasing Frequency [Java]
      • 52. Maximum Number of Pairs in Array [Java, Python]
      • 56. Custom Sort String [Java, Python]
  • Backtracking
    • 3. Amount of Time for Binary Tree to Be Infected [Java, Python]
    • 29. Power Set LCCI [Java]
    • 50. Merge Sort [Java]
  • Binary Search
    • 32. My Calendar II [Java, Python]
  • Conditional Logic
    • 2. Add Edges to Make Degrees of All Nodes Even [Java]
  • Depth-first Search
    • 29. Power Set LCCI [Java]
    • 46. Number of Paths with Max Score [Java]
    • 51. Quick Sort [Java]
    • 53. Can I Win [Java, Python]
  • Dichotomy
    • 4. Search in Rotated Sorted Array [Java]
  • Difference Array
    • 5. Jump Game VII [Java]
    • 37. Zero Array Transformation II [Java]
  • Dynamic Programming
    • Standard
      • 6. Climbing Stairs [Java]
      • 7. Count All Valid Pickup and Delivery Options [Java]
      • 8. Decode Ways II [Java]
      • 9. Make the XOR of All Segments Equal to Zero [Java]
      • 10. Maximize Value of Function in a Ball Passing Game [Java]
      • 11. Minimum Deletions to Make String Balanced [Java]
      • 12. Stone Game [Java]
      • 13. Target Sum [Java]
    • Problem Breakdown
      • 35. Maximum Multiplication Score [Java]
  • HashMap
    • 30. Count Common Words With One Occurrence [Java]
    • 45. Intersection of Two Arrays II [Java, Python]
  • Heap
    • 39. Trapping Rain Water II [Java]
    • 43. Total Cost to Hire K Workers [Java]
  • Fenwick Tree
    • 14. Distribute Elements Into Two Arrays II [Java]
    • 55. Maximum Balanced Subsequence Sum [Java, Python, C++, Golang]
  • Graph
    • Dijkstra
      • 41. Path with Maximum Probability [Java]
    • Bellman-Ford
      • 41. Path with Maximum Probability [Java]
  • Greedy
    • 15. Max Difference You Can Get From Changing an Integer [Java]
    • 16. Maximum Length of Subarray With Positive Product [Java]
  • Math
    • 17. Construct the Minimum Bitwise Array II [Java]
    • 18. Egg Drop With 2 Eggs and N Floors [Java]
    • 19. Find Number of Ways to Reach the K-th Stair [Java]
    • 20. Minimum Moves to Capture The Queen [Java]
  • Pattern Rule
    • 38. Transform to Chessboard [Java]
  • Precomputation
    • 21. Range Product Queries of Powers [Java]
  • Segment Tree
    • 32. My Calendar II [Java, Python]
  • Sliding Window
    • Standard
      • 22. Find the Longest Equal Subarray [Java]
    • Subset Concatenation
      • 40. Count Subarrays Where Max Element Appears at Least K Times [Java]
    • Fixed-size Window
      • 44. Find Indices With Index and Value Difference I [Java]
  • Sorting
    • 49. Bubble Sort [Java]
    • 50. Merge Sort [Java]
    • 51. Quick Sort [Java]
  • Stack
    • Monotonic Stack
      • 47. Beautiful Towers II [Java]
  • String
    • 23. License Key Formatting [Java]
    • 57. Valid Palindrome [Java, Python]
  • Traversal
    • 24. Find the Number of Ways to Place People I [Java]
    • 25. Maximum Number of Operations With the Same Score I [Java]
    • 29. Power Set LCCI [Java]
    • 36. Find Triangular Sum of an Array [Java]
    • 42. Count Prefix and Suffix Pairs I [Java]
    • 48. Longest Common Prefix [Java]
    • 49. Bubble Sort [Java]
  • Two Pointer
    • 26. Boats to Save People [Java]
    • 27. Find the Lexicographically Largest String From the Box I [Java]
    • 28. Merge Sorted Array [Java]
    • 54. 3Sum Closest [Java, Python]
    • 57. Valid Palindrome [Java, Python]
  • Union-Find
    • 33. Graph Connectivity With Threshold [Java]
• SQL Problems
  • 1. Odd and Even Transactions [MySQL, Oracle]
  • 2. Find Customer Referee [MySQL, Oracle]