Amazon Interview Experience SDE 1 (DSA-focused)
- Posted
- 20 Apr 2026
Summary
I completed three interview rounds focusing on DSA and system thinking, and identified the core patterns needed to succeed.
How it went
Had 3 rounds — here are the key problems asked:
Round 1:
- Longest island → perimeter + coordinates (DFS/BFS)
- Minimum arrows to burst balloons (Greedy - intervals)
Round 2:
- Convert BST → height-balanced BST (Inorder + recursion)
- First missing positive (Array indexing / cyclic sort)
Round 3:
-
No direct DSA
-
Focus shifted to system thinking + deep dive on past projects
-
Data structures:
- Monthly sales → HashMap
- Top-K items → Heap / Priority Queue
Key Takeaways:
- Strong grip on core patterns is enough (DFS, Greedy, Heap, Arrays, Trees)
- Optimization + edge cases matter
- Be ready to explain your approach clearly
Prep used: Striver Sheet + LeetCode 75/150
If you're preparing for Amazon, these patterns cover most of the ground.
Questions asked (4)
- 01
Longest Island
Data Structures & Algorithms
Find the longest island in a grid using DFS/BFS to compute its perimeter and coordinates.
- 02
Minimum Number of Arrows to Burst Balloons
Data Structures & Algorithms
Given intervals representing balloons, determine the minimum number of arrows needed to burst all balloons using a greedy interval approach.
- 03
Convert BST to Height-Balanced BST
Data Structures & Algorithms
Convert a given binary search tree into a height-balanced BST using inorder traversal and recursion.
- 04
First Missing Positive
Data Structures & Algorithms
Find the first missing positive integer in an unsorted array using array indexing / cyclic sort.
How they prepared
Prep used: Striver Sheet + LeetCode 75/150