Cracking Amazon's Software Engineer Role: Tackling Subarray Sums Divisible by K

Software Engineering
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amazon | Software Engineer | Interview Experience

Interview Date: Not specified
Result: Rejected
Difficulty: Not specified

Interview Process

The interview process included an online assessment (OA) that consisted of two coding questions, each with a duration of 70 minutes, followed by a working simulation, work style assessment, and a personality test. The focus here is primarily on the coding questions.

Technical Questions

  1. Subarray Sums Divisible by K
    Given an array of integers arr and an integer k, calculate how many consecutive subarrays satisfy the condition (sum of all elements in the subarray) % k == (length of the subarray). A brute force solution will result in a time limit exceeded (TLE) error; the optimal solution involves using prefix sums and a hash map.
    Example: arr = [1, 3, 2, 4], k = 4
    Valid subarrays: [1], [2, 4]
    Output: 2

  2. Minimum Flips to Make Substrings Identical
    Given a binary string of even length, the objective is to split it into a number of substrings that minimize the number of character flips (0->1 or 1->0) while also minimizing the number of final substrings. Each substring must have an even length and all characters must be identical after flipping.
    Example: For the string "100110", the minimum number of flips required is 3 to achieve "111111".
    Output: 1

Tips & Insights

The candidate noted that they did not practice enough questions prior to the interview and did not thoroughly review all test cases, which contributed to their rejection. They emphasized the importance of preparation and wish others good luck in their interview journeys.