Top 50 DSA Questions for Amazon Interviews

Amazon DSA patterns at a glance

Amazon's coding rounds favor practical medium problems over obscure hard puzzles. The Online Assessment typically has 2 medium problems; onsite rounds add follow-up optimizations. These 50 questions cover the highest-frequency patterns from Amazon-tagged problems.

Arrays and strings (10)

• Two Sum / Three Sum variants.
• Maximum subarray (Kadane's algorithm).
• Merge intervals.
• Product of array except self.
• Container with most water.
• Longest substring without repeating characters.
• Group anagrams.
• Rotate array / find minimum in rotated sorted array.
• Top K frequent elements.
• Trapping rain water.

Trees and graphs (10)

• Level order traversal (BFS).
• Validate binary search tree.
• Lowest common ancestor.
• Number of islands (grid DFS/BFS).
• Course schedule (topological sort).
• Clone graph.
• Word ladder (BFS shortest path).
• Diameter of binary tree.
• Serialize and deserialize binary tree.
• Kth smallest element in BST.

Sliding window and two pointers (8)

• Minimum window substring.
• Longest repeating character replacement.
• Fruit into baskets.
• Subarray sum equals K.
• Find all anagrams in a string.
• Max consecutive ones III.
• 3Sum closest.
• Sort colors (Dutch national flag).

Heaps and binary search (7)

• Kth largest element in an array.
• Merge K sorted lists.
• Find median from data stream.
• Search in rotated sorted array.
• Koko eating bananas (binary search on answer).
• Meeting rooms II.
• Reorganize string.

Dynamic programming and greedy (8)

• Coin change.
• Longest increasing subsequence.
• House robber I and II.
• Unique paths.
• Task scheduler (greedy + heap).
• Partition labels.
• Jump game I and II.
• Decode ways.

Amazon OA tips

Practice on a plain editor without autocomplete. Aim to finish both problems with working code. Run Amazon-style mocks on InterviewVeda before your OA date.

• Read all test cases before coding.
• Handle edge cases: empty input, single element, duplicates.
• State complexity before optimizing.
• Do not spend more than 5 minutes stuck — write brute force first.

7-day Amazon cram plan

If your OA is next week: Day 1–2 arrays/strings, Day 3 trees, Day 4 graphs/BFS, Day 5 heaps, Day 6 DP/greedy, Day 7 timed mock OAs.