Problems

4,051+ problems · 966 Easy · 2113 Medium · 972 Hard

Title	Solution	Practice	Difficulty	Companies	Topics
1. Two Sum	Solution	Solve	Easy	Accenture+126	Array Hash Table
2. Add Two Numbers	Solution	Solve	Medium	Accenture+36	Linked List Math+1
3. Longest Substring Without Repeating Characters	Solution	Solve	Medium	Accenture+104	Hash Table Sliding Window+1
4. Median of Two Sorted Arrays	Solution	Solve	Hard	Accenture+44	Array Binary Search+1
5. Longest Palindromic Substring	Solution	Solve	Medium	Accenture+81	Dynamic Programming String+1
6. Zigzag Conversion	Solution	Solve	Medium	Amazon+18	String
7. Reverse Integer	Solution	Solve	Medium	Accenture+21	Math
8. String to Integer (atoi)	Solution	Solve	Medium	Accenture+20	String
9. Palindrome Number	Solution	Solve	Easy	Accenture+31	Math
10. Regular Expression Matching	Solution	Solve	Hard	Accenture+24	Dynamic Programming Recursion+1
11. Container With Most Water	Solution	Solve	Medium	Accenture+57	Array Greedy+1
12. Integer to Roman	Solution	Solve	Medium	Accenture+30	Hash Table Math+1
13. Roman to Integer	Solution	Solve	Easy	Accenture+35	Hash Table Math+1
14. Longest Common Prefix	Solution	Solve	Easy	Accenture+59	String Trie
15. 3Sum	Solution	Solve	Medium	Accenture+56	Array Sorting+1
16. 3Sum Closest	Solution	Solve	Medium	Amazon+10	Array Sorting+1
17. Letter Combinations of a Phone Number	Solution	Solve	Medium	Accenture+33	Backtracking Hash Table+1
18. 4Sum	Solution	Solve	Medium	Accenture+19	Array Sorting+1
19. Remove Nth Node From End of List	Solution	Solve	Medium	Accenture+17	Linked List Two Pointers
20. Valid Parentheses	Solution	Solve	Easy	Accenture+112	Stack String
21. Merge Two Sorted Lists	Solution	Solve	Easy	Accenture+35	Linked List Recursion
22. Generate Parentheses	Solution	Solve	Medium	Accenture+39	Backtracking Dynamic Programming+1
23. Merge k Sorted Lists	Solution	Solve	Hard	Airbnb+49	Divide and Conquer Heap (Priority Queue)+2
24. Swap Nodes in Pairs	Solution	Solve	Medium	Altimetrik+12	Linked List Recursion
25. Reverse Nodes in k-Group	Solution	Solve	Hard	Amazon+26	Linked List Recursion
26. Remove Duplicates from Sorted Array	Solution	Solve	Easy	Accenture+25	Array Two Pointers
27. Remove Element	Solution	Solve	Easy	Adobe+9	Array Two Pointers
28. Find the Index of the First Occurrence in a String	Solution	Solve	Easy	Amazon+15	String String Matching+1
29. Divide Two Integers	Solution	Solve	Medium	Amazon+7	Bit Manipulation Math
30. Substring with Concatenation of All Words	Solution	Solve	Hard	Amazon+9	Hash Table Sliding Window+1
31. Next Permutation	Solution	Solve	Medium	Accenture+31	Array Two Pointers
32. Longest Valid Parentheses	Solution	Solve	Hard	Accenture+24	Dynamic Programming Stack+1
33. Search in Rotated Sorted Array	Solution	Solve	Medium	Accenture+52	Array Binary Search
34. Find First and Last Position of Element in Sorted Array	Solution	Solve	Medium	Accenture+28	Array Binary Search
35. Search Insert Position	Solution	Solve	Easy	Accenture+11	Array Binary Search
36. Valid Sudoku	Solution	Solve	Medium	Amazon+25	Array Hash Table+1
37. Sudoku Solver	Solution	Solve	Hard	Amazon+16	Array Backtracking+2
38. Count and Say	Solution	Solve	Medium	Amazon+12	String
39. Combination Sum	Solution	Solve	Medium	Airbnb+25	Array Backtracking
40. Combination Sum II	Solution	Solve	Medium	Adobe+14	Array Backtracking
41. First Missing Positive	Solution	Solve	Hard	Amazon+32	Array Hash Table
42. Trapping Rain Water	Solution	Solve	Hard	Accenture+72	Array Dynamic Programming+3
43. Multiply Strings	Solution	Solve	Medium	Amazon+16	Math Simulation+1
44. Wildcard Matching	Solution	Solve	Hard	Amazon+16	Dynamic Programming Greedy+2
45. Jump Game II	Solution	Solve	Medium	Adobe+25	Array Dynamic Programming+1
46. Permutations	Solution	Solve	Medium	Agoda+24	Array Backtracking
47. Permutations II	Solution	Solve	Medium	Amazon+8	Array Backtracking
48. Rotate Image	Solution	Solve	Medium	Accenture+35	Array Math+1
49. Group Anagrams	Solution	Solve	Medium	Accolite+86	Array Hash Table+2
50. Pow(x, n)	Solution	Solve	Medium	Accenture+21	Math Recursion