Unfoldd

Coding Arena

200+ curated problems · 14 languages · Daily challenges · AI analysis

Problem List

1. Two Sum

EasyArrayGoogleAmazon

2. Contains Duplicate

EasyArrayAppleMicrosoft

3. Missing Number

EasyArrayAmazon

4. Valid Anagram

EasyStringUberMeta

5. Find Minimum

EasyArrayOracle

6. Search in Rotated Sorted Array

MediumArrayAmazon

7. Container With Most Water

MediumArrayGoogle

8. Maximum Subarray

MediumDynamic ProgrammingMicrosoftAmazon

9. Longest Substring Without Repeating Characters

MediumStringGoogleMeta

10. Product of Array Except Self

MediumArrayAmazonApple

11. Minimum Window Substring

HardStringMetaUber

12. Sliding Window Maximum

HardQueueAmazon

13. Largest Rectangle in Histogram

HardStackMetaAmazon

14. Median of Two Sorted Arrays

HardArrayGoogleMicrosoft

15. Trapping Rain Water

HardArrayGoogleAmazon

16. Longest Substring Without Repeating Characters

MediumStringGoogleAmazon

17. Add Two Numbers

MediumArrayGoogleAmazon

18. Merge Two Sorted Lists

EasyLinkedListAmazonMicrosoft

19. Reverse Linked List

EasyLinkedListGoogleMeta

20. Linked List Cycle

EasyLinkedListAmazon

21. Merge K Sorted Lists

HardLinkedListGoogle

22. Remove Nth Node From End

MediumLinkedListMicrosoft

23. Reorder List

MediumLinkedListMeta

24. Copy List with Random Pointer

MediumLinkedListAmazon

25. Reverse Nodes in K Group

HardLinkedListGoogle

26. LRU Cache

MediumArrayGoogleAmazon

27. Valid Parentheses

EasyStackAmazon

28. Generate Parentheses

MediumStackGoogle

29. Daily Temperatures

MediumStackAmazon

30. Next Greater Element I

EasyArrayMicrosoft

31. Next Greater Element II

MediumArrayGoogle

32. Decode String

MediumArrayMeta

33. Evaluate Reverse Polish Notation

MediumStackAmazon

34. Min Stack

MediumStackGoogle

35. Basic Calculator

HardStackGoogle

36. Binary Tree Inorder Traversal

37. Binary Tree Level Order Traversal

MediumTreeMicrosoft

38. Maximum Depth of Binary Tree

39. Diameter of Binary Tree

40. Same Tree

41. Symmetric Tree

EasyTreeMicrosoft

42. Validate BST

MediumTreeGoogle

43. Kth Smallest in BST

MediumTreeAmazon

44. Lowest Common Ancestor BST

MediumTreeMicrosoft

45. Binary Tree Right Side View

MediumTreeGoogleMeta

46. Serialize and Deserialize Binary Tree

HardTreeGoogleMeta

47. Number of Islands

MediumGraphGoogleMeta

48. Clone Graph

MediumGraphGoogleMeta

49. Course Schedule

MediumGraphGoogleMeta

50. Course Schedule II

MediumGraphGoogleMeta

51. Pacific Atlantic Water Flow

MediumGraphGoogleMeta

52. Rotting Oranges

MediumGraphGoogleMeta

53. Word Ladder

HardGraphGoogleMeta

54. Accounts Merge

MediumGraphGoogleMeta

55. Network Delay Time

MediumGraphGoogleMeta

56. Cheapest Flights Within K Stops

MediumGraphGoogleMeta

57. Climbing Stairs

EasyDynamic ProgrammingGoogleMeta

58. House Robber

MediumDynamic ProgrammingGoogleMeta

59. House Robber II

MediumDynamic ProgrammingGoogleMeta

60. Coin Change

MediumDynamic ProgrammingGoogleMeta

61. Longest Increasing Subsequence

MediumDynamic ProgrammingGoogleMeta

62. Partition Equal Subset Sum

MediumDynamic ProgrammingGoogleMeta

63. Word Break

MediumDynamic ProgrammingGoogleMeta

64. Edit Distance

HardDynamic ProgrammingGoogleMeta

65. Longest Common Subsequence

MediumDynamic ProgrammingGoogleMeta

66. Decode Ways

MediumDynamic ProgrammingGoogleMeta

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