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.