Most Asked Amazon DSA Questions

Array and String Favorites

• Two Sum, Three Sum variants.
• Longest substring without repeating characters (sliding window).
• Trapping rain water (two pointers or stack).
• Group anagrams (hashing).
• Merge intervals, insert interval.

Tree and Graph

• Level order traversal, zigzag traversal.
• Lowest common ancestor (BST and general tree).
• Number of islands (BFS/DFS).
• Clone graph, clone linked list with random pointer.
• Course schedule (topological sort).

Dynamic Programming

• Climbing stairs, house robber.
• Longest increasing subsequence.
• Coin change.
• Word break.

Design and System Design Lite

• LRU cache (hash map + doubly linked list).
• Min stack.
• Serialize/deserialize binary tree.

Summary

Focus on these patterns; Amazon often repeats similar ideas. Practice on Preplume(/) and time yourself.