QA / SDET · Online Assessment · Coding

Amazon — QA / SDET

Level: Intern

Round: Online Assessment · Type: Coding · Difficulty: 6/10 · Interviewer: Unfriendly

Topics: Greedy Algorithms, Prefix Sum, Binary Search

Location: Seattle, WA

Interview date: 2026-01-11

Summary

The online assessment consisted of two coding questions.

Question 1: Determine optimal samples by replacing '?' to minimize the total overhead. This is a greedy problem.

Question 2: Find the maximum median. Initially, I used binary search, passing 8/15 test cases. After rereading the problem, I realized it was a greedy + mathematical problem, not a binary search or prefix sum problem.

Details

The online assessment questions were:

1. Determine optimal samples: Replace all '?' characters to minimize the sum of overhead at all positions. This is a greedy algorithm problem.

2. Get maximum median: My initial approach used binary search, but only passed 8/15 test cases. I realized it's a greedy + mathematical conclusion problem.

Key takeaway: When encountering problems with 'forced increment and decrement' operations and the 'target is median/maximum/minimum', consider whether all operations can be focused on a key position and if 'resource transfer/cost' truly exists.

Preparation Tips:

• Avoid automatically applying LeetCode templates. Carefully analyze the problem constraints and requirements before implementing a solution.
• Practice greedy and mathematical reasoning questions.