DSA Practice Sheet

Welcome to your comprehensive DSA Practice Sheet. Below are 30 carefully curated algorithm and data structure practice questions, grouped by topic and difficulty. Each links to its LeetCode problem. Use the filters at the top to jump right into Beginner, Intermediate, or Advanced.

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Filters

To quickly find questions by difficulty, use these links:

• Beginner
• Intermediate
• Advanced

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Beginner

1. Two Sum – Array – LeetCode
2. Reverse String – String – LeetCode
3. Valid Parentheses – Stack – LeetCode
4. Merge Two Sorted Lists – Linked List – LeetCode
5. Maximum Subarray – Arrays / Kadane's – LeetCode
6. Climbing Stairs – DP (simple) – LeetCode
7. Best Time to Buy and Sell Stock – Array / Greedy – LeetCode
8. Symmetric Tree – Tree – LeetCode
9. Path Sum – Tree – LeetCode
10. Intersection of Two Arrays II – Hash Table – LeetCode

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Intermediate

11. Add Two Numbers – Linked List – LeetCode
12. Count and Say – String / Recursion – LeetCode
13. Binary Tree Inorder Traversal – Tree / Stack – LeetCode
14. Longest Substring Without Repeating Characters – Sliding Window – LeetCode
15. Container With Most Water – Two Pointers – LeetCode
16. 3Sum – Two Pointers – LeetCode
17. Letter Combinations of a Phone Number – Backtracking – LeetCode
18. Word Search – Backtracking – LeetCode
19. Coin Change – DP (classic) – LeetCode
20. Number of Islands – DFS / BFS – LeetCode

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Advanced

21. Merge k Sorted Lists – Heap – LeetCode
22. Maximum Subarray Sum with Size K (sliding window variant) – LeetCode
23. Trapping Rain Water – Two Pointers – LeetCode
24. Serialize and Deserialize Binary Tree – Tree / Design – LeetCode
25. LRU Cache – Design – LeetCode
26. Word Ladder – BFS / Graph – LeetCode
27. Longest Consecutive Sequence – Union-Find or Hash – LeetCode
28. Subarray Sum Equals K – Hash – LeetCode
29. Minimum Window Substring – Sliding Window – LeetCode
30. N-Queens – Backtracking – LeetCode

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Happy practicing — you've got this.