Algorithms

Sorting, searching, greedy, recursion, dynamic programming and more.

106 problems

Title	Tags	Acceptance	Difficulty
1. Two Sum	Array · Hash Map	—	Easy
2. Maximum Subarray Sum	Array · Dynamic Programming · Kadane	—	Medium
3. Binary Search	Binary Search · Array	—	Easy
4. Climbing Stairs	Dynamic Programming · Recursion	—	Easy
5. Coin Change	Dynamic Programming	—	Medium
6. Longest Increasing Subsequence	Dynamic Programming · Binary Search	—	Medium
7. Activity Selection	Greedy · Sorting	—	Medium
8. Longest Common Subsequence	Dynamic Programming · String	—	Medium
9. Edit Distance	Dynamic Programming · String	—	Hard
10. 0/1 Knapsack	Dynamic Programming	—	Hard
11. N-Queens Count	Backtracking	—	Hard
12. Sliding Window Maximum	Deque · Sliding Window	—	Hard
13. Shortest Path in a Graph	Graph · BFS	—	Medium
14. Number of Islands	Graph · DFS · Matrix	—	Medium
15. Count Primes	Sieve of Eratosthenes	—	Medium
16. Longest Palindromic Substring	String · Expand Around Center	—	Medium
17. Best Time to Buy and Sell Stock	Array · Greedy	—	Easy
18. Majority Element	Array · Boyer-Moore Voting	—	Easy
19. Trapping Rain Water	Two Pointers · Array	—	Hard
20. Next Permutation	Permutation	—	Medium
21. Sort an Array	Sorting	—	Easy
22. Sort in Descending Order	Sorting	—	Easy
23. Sort by Absolute Value	Custom Sort	—	Easy
24. Sort Words by Length	Custom Sort	—	Easy
25. First Position Not Less Than X	Binary Search	—	Easy
26. First and Last Occurrence	Binary Search	—	Easy
27. Search in Rotated Sorted Array	Binary Search	—	Medium
28. Minimum in Rotated Sorted Array	Binary Search	—	Medium
29. K-th Smallest Element	Sorting · Selection	—	Easy
30. Aggressive Cows	Binary Search on Answer	—	Hard
31. Allocate Books	Binary Search on Answer	—	Hard
32. Eating Speed	Binary Search on Answer	—	Medium
33. Median of Two Sorted Arrays	Binary Search · Merge	—	Hard
34. Count Elements ≤ X	Binary Search · Sorting	—	Easy
35. Triplets with Zero Sum	Two Pointers · Sorting	—	Medium
36. Pair Sum Closest to Target	Two Pointers	—	Medium
37. All Subsets	Backtracking · Bitmask	—	Medium
38. All Permutations	Backtracking	—	Medium
39. Unique Permutations	Backtracking	—	Medium
40. Combinations of K	Backtracking	—	Medium
41. Combination Sum	Backtracking	—	Medium
42. Subset Sum	Dynamic Programming	—	Medium
43. N-Queens Solutions Count	Backtracking	—	Hard
44. Word Search	DFS · Backtracking	—	Medium
45. Phone Keypad Combinations	Backtracking	—	Medium
46. Generate Parentheses	Backtracking	—	Medium
47. Tower of Hanoi	Recursion	—	Easy
48. Grid Paths	Combinatorics · Recursion	—	Easy
49. Palindrome Partitions	Backtracking	—	Medium
50. Gray Code	Bits · Recursion	—	Medium
51. Sudoku Solver	Backtracking	—	Hard
52. Rat in a Maze	Backtracking · DFS	—	Medium
53. House Robber	Dynamic Programming	—	Medium
54. House Robber (Circle)	Dynamic Programming	—	Medium
55. Min Cost Climbing Stairs	Dynamic Programming	—	Easy
56. Grid Paths with Obstacles	Dynamic Programming · Grid	—	Medium
57. Minimum Path Sum	Dynamic Programming · Grid	—	Medium
58. Triangle Minimum Path	Dynamic Programming	—	Medium
59. 0/1 Knapsack	Knapsack	—	Medium
60. Unbounded Knapsack	Knapsack	—	Medium
61. Coin Change — Number of Ways	Dynamic Programming · Counting	—	Medium
62. Longest Common Substring	Dynamic Programming	—	Medium
63. Longest Palindromic Subsequence	Dynamic Programming	—	Medium
64. Minimum Insertions for Palindrome	Dynamic Programming	—	Medium
65. Word Break	Dynamic Programming	—	Medium
66. Partition Equal Subset Sum	Knapsack	—	Medium
67. Target Sum with Signs	Dynamic Programming · Counting	—	Medium
68. Number of Longest Increasing Subsequences	Dynamic Programming	—	Hard
69. Maximum Product Subarray	Dynamic Programming	—	Medium
70. Jump Game	Greedy	—	Medium
71. Minimum Jumps	Greedy · BFS	—	Medium
72. Rod Cutting	Dynamic Programming	—	Medium
73. Egg Dropping	Dynamic Programming	—	Hard
74. Matrix Chain Multiplication	Interval DP	—	Hard
75. Ways to Make an Expression	Interval DP	—	Hard
76. Paint the Fence	Dynamic Programming · Counting	—	Medium
77. Count Binary Search Trees	Catalan	—	Medium
78. Dice Sum Ways	Dynamic Programming · Counting	—	Medium
79. Longest Bitonic Subsequence	Dynamic Programming	—	Medium
80. Largest Square of Ones	Dynamic Programming · Grid	—	Medium
81. Distinct Subsequence Count	Dynamic Programming · Counting	—	Hard
82. Wildcard Matching	Dynamic Programming	—	Hard
83. Regular Expression Matching	Dynamic Programming	—	Hard
84. Stock Trading with Cooldown	State Machine DP	—	Medium
85. Stock Trading with K Transactions	Dynamic Programming	—	Hard
86. Minimum Subset Difference	Knapsack	—	Medium
87. Count Subsets with Sum	Knapsack · Counting	—	Medium
88. Longest Arithmetic Subsequence	Dynamic Programming · Hash Map	—	Medium
89. Frog Jump with K	Dynamic Programming	—	Easy
90. Vacation Plan	Dynamic Programming	—	Medium
91. Perfect Squares	Dynamic Programming	—	Medium
92. Binary Strings Without Consecutive Ones	Dynamic Programming · Fibonacci	—	Easy
93. Domino Tiling 2×N	Dynamic Programming	—	Easy
94. Max Sum without Three Consecutive	Dynamic Programming	—	Medium
95. Maximum Meetings in One Room	Interval Scheduling	—	Easy
96. Fractional Knapsack	Greedy · Sorting	—	Easy
97. Minimum Notes (Indian Currency)	Greedy	—	Easy
98. Job Sequencing with Deadlines	Greedy · Sorting	—	Medium
99. Minimum Arrows to Burst Balloons	Intervals	—	Medium
100. Remove Overlapping Intervals	Intervals	—	Medium
101. Gas Station Circuit	Greedy	—	Medium
102. Candy Distribution	Greedy · Two Passes	—	Hard
103. Assign Cookies	Greedy · Sorting	—	Easy
104. Boats to Save People	Two Pointers · Greedy	—	Medium
105. Largest Number	Custom Sort	—	Medium
106. Minimum Sum from Digits	Greedy	—	Easy

106 of 106 problems