DSA Interview Preparation: Must-Solve Problems by Topic

Arrays and Strings

Must-Solve Problems

• Two Sum
• Best Time to Buy and Sell Stock
• Longest Substring Without Repeating Characters
• Container With Most Water
• 3Sum
• Merge Intervals
• Product of Array Except Self

Linked Lists

Must-Solve Problems

• Reverse Linked List
• Merge Two Sorted Lists
• Linked List Cycle
• Remove Nth Node From End
• Add Two Numbers

Trees

Must-Solve Problems

• Maximum Depth of Binary Tree
• Same Tree
• Invert Binary Tree
• Binary Tree Level Order Traversal
• Validate Binary Search Tree
• Lowest Common Ancestor

Graphs

Must-Solve Problems

• Number of Islands
• Clone Graph
• Course Schedule
• Word Ladder
• Network Delay Time

Dynamic Programming

Must-Solve Problems

• Climbing Stairs
• House Robber
• Longest Increasing Subsequence
• Coin Change
• Edit Distance
• Longest Common Subsequence

Greedy Algorithms

Must-Solve Problems

• Jump Game
• Gas Station
• Non-overlapping Intervals
• Partition Labels

Backtracking

Must-Solve Problems

• Combination Sum
• Permutations
• N-Queens
• Word Search

Study Strategy

1. Solve each problem yourself first
2. Understand the approach and time/space complexity
3. Practice similar problems
4. Review and revise regularly

Conclusion

Mastering these problems will give you a strong foundation for coding interviews. Focus on understanding patterns, not just memorizing solutions.