50 LeetCode Problems Every Software Engineer Must Solve Before a FAANG Interview

Solving these 50 problems with full understanding prepares a candidate for 85-90% of coding interview questions at Google, Amazon, Meta, Microsoft, and Apple.

How to Use This List

• Solve 3-5 problems per day for 2-3 weeks
• Understand the pattern, not just the solution
• Practice explaining your approach out loud
• Use AissenceAI coding copilot for step-by-step help

Array and String (8 problems)

1. Two Sum (Easy) - HashMap - Google, Amazon
2. Best Time to Buy and Sell Stock (Easy) - Sliding window - Amazon
3. Container With Most Water (Medium) - Two pointers - Meta
4. 3Sum (Medium) - Two pointers + sort - Google
5. Product of Array Except Self (Medium) - Prefix/suffix - Amazon
6. Maximum Subarray (Medium) - Kadane algorithm - Microsoft
7. Merge Intervals (Medium) - Sort + merge - Google
8. Trapping Rain Water (Hard) - Two pointers - Google

Tree (7 problems)

9-15. Maximum Depth, Validate BST, Level Order, LCA, Serialize/Deserialize, Right Side View, Construct from Preorder/Inorder

Dynamic Programming (8 problems)

16-23. Climbing Stairs, Coin Change, LIS, Word Break, Unique Paths, LCS, Edit Distance, Decode Ways

Graph (5 problems)

24-28. Number of Islands, Clone Graph, Course Schedule, Pacific Atlantic, Network Delay

3-Week Practice Plan

Week	Focus	Hours/Day
1	Arrays, Strings, Linked Lists, Stack	2-3
2	Trees, Graphs, Binary Search, Backtracking	2-3
3	DP, Heap, Review weak patterns	2-3

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