CODING INTERVIEW PREPARATION

Solved Problems

Status	Level	Problem	Solution Preview	Approach (Language)
✅	Easy	1. Two Sum		Array (Python)
✅	Easy	2. Concatenation of Array		Array (Python)
✅	Easy	3. Reverse String		String Manipulation (Python)
✅	Easy	4. Contains Duplicate		Hash Table (C++)
✅	Easy	5. Valid Palindrome		Two Pointers (Python)
✅	Easy	6. Best Time to Buy and Sell Stock		Dynamic Programming (Python)
✅	Easy	7. Valid Parentheses		Stack (Python)
✅	Easy	8. Binary Search		Binary Search (Python)
✅	Easy	9. Reverse Linked List		Linked List (Python)
✅	Easy	10. Invert Binary Tree		Binary Tree (Python)
✅	Medium	11. Top K Frequent Elements		Heap/Hash Table (Python)
✅	Medium	12. Two Sum II - Input Array Is Sorted		Binary Search (Python)
✅	Medium	13. Longest Substring Without Repeating Characters		Sliding Window (Python)
✅	Medium	14. Min Stack		Stack (Python)
✅	Medium	15. Evaluate Reverse Polish Notation		Stack (Python)
✅	Medium	16. Search a 2D Matrix		Binary Search (Python)
✅	Medium	17. Reorder List		Linked List (Python)
✅	Medium	18. Lowest Common Ancestor of a Binary Search Tree		Binary Search Tree (Python)
✅	Medium	19. Subsets		Backtracking (Python)
✅	Medium	20. K Closest Points to Origin		Heap/Sorting (Python)
✅	Medium	21. Number of Islands		DFS (Python)
✅	Medium	22. Sum of Two Integers		Bit Manipulation (Python)
✅	Medium	23. Maximum Subarray		Kadane's Algorithm (Python)
✅	Medium	24. Insert Interval		Greedy (Python)
✅	Medium	25. Rotate Image		Matrix Manipulation (Python)
✅	Easy	26. Climbing Stairs		Dynamic Programming (Python)
✅	Medium	27. Unique Paths		Dynamic Programming (Python)
✅	Easy	28. Min Cost Climbing Stairs		Dynamic Programming (Python)
✅	Medium	29. Longest Common Subsequence		Dynamic Programming (Python)
✅	Medium	30. House Robber		Dynamic Programming (Python)
✅	Medium	31. Best Time to Buy and Sell Stock with Cooldown		Dynamic Programming (Python)
✅	Medium	32. Max Area of Island		DFS (Python)
✅	Easy	33. Last Stone Weight		Heap (Python)
✅	Medium	34. Kth Largest Element in an Array		Heap/Quickselect (Python)
✅	Medium	35. Combination Sum		Backtracking (Python)
✅	Medium	36. Combination Sum II		Backtracking (Python)
✅	Medium	37. Jump Game		Greedy (Python)
✅	Hard	38. Jump Game II		Greedy (Python)
✅	Medium	39. 3Sum		Two Pointers (Python)
✅	Medium	40. Koko Eating Bananas		Binary Search (Python)
✅	Easy	41. Merge Two Sorted Lists		Linked List (Python)
✅	Easy	42. Linked List Cycle		Linked List (Python)
✅	Medium	43. Binary Tree Level Order Traversal		Binary Tree (Python)
✅	Medium	44. Binary Tree Right Side View		Binary Tree (Python)
✅	Easy	45. Maximum Depth of Binary Tree		Binary Tree (Python)
✅	Medium	46. Valid Sudoku		Hash Table (Python)
✅	Medium	47. Longest Repeating Character Replacement		Sliding Window (Python)
✅	Medium	48. Daily Temperatures		Stack (Python)
✅	Medium	49. Generate Parentheses		Backtracking (Python)
✅	Medium	50. Remove Nth Node From End of List		Linked List (Python)
✅	Medium	51. Copy List with Random Pointer		Linked List (Python)
✅	Medium	52. Permutations		Backtracking (Python)
✅	Medium	53. Count Good Nodes in Binary Tree		Binary Tree (Python)
✅	Medium	54. Clone Graph		Graph (Python)
✅	Medium	55. Rotting Oranges		BFS (Python)
✅	Medium	56. House Robber II		Dynamic Programming (Python)
✅	Medium	57. Longest Palindromic Substring		Dynamic Programming (Python)
✅	Medium	58. Course Schedule		Graph (Python)
✅	Medium	59. Gas Station		Greedy (Python)
✅	Medium	60. Hand of Straights		Greedy/minHeap (Python)
✅	Medium	61. Find Minimum in Rotated Sorted Array		Binary Search (Python)
✅	Medium	62. Add Two Numbers		Linked List (Python)
✅	Medium	63. Palindromic Substrings		Expand Around Center (Python)
✅	Medium	64. Decode Ways		Recursion (Python)
✅	Medium	65. Non-overlapping Intervals		Greedy/Sorting (Python)
✅	Medium	66. Spiral Matrix		Matrix Traversal (Python)
✅	Medium	67. Longest Consecutive Sequence		Hash Set (Python)

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