Software Engineer · Online Assessment · Coding

Amazon — Software Engineer ✅ Passed

Level: Intern

Round: Online Assessment · Type: Coding · Difficulty: 5/10 · Duration: 60 min · Interviewer: Unfriendly

Topics: Hash Table, Sorting, Arrays

Location: Seattle, WA, US

Interview date: 2025-12-27

Summary

I completed an online assessment with two coding questions.

Details

I had an online assessment consisting of two coding questions.

Question 1: Given an integer array where each element represents an error code, reorder the error codes based on priority. Priority rules:

1. Frequency: Less frequent errors are more important and should come first.
2. Value: If frequencies are the same, the smaller error code value has higher priority. Output: Return the sorted original array (containing duplicates).

My solution: I used a hash table and a custom key for sorting.

1. Use collections.Counter to count frequencies.
2. Use sort() with a key set to (frequency, error code value).
3. Return the sorted result.

Question 2: Given a sequence $A = [a_1, a_2, ..., a_n]$ of length $n$.

Select any closed interval [i, j] (where $1 < i < j < n$) and a positive integer x, increment all elements a_k within that interval by x. The final sequence must satisfy a_i < a_i+1 (non-decreasing sequence). Minimize the cumulative sum of x across all operations

My Solution: The core idea is that the minimum total sum of x is equal to the sum of all differences where a previous element is greater than the following element. By traversing the array and comparing a[i] and a[i-1]: If a[i] < a[i-1], then there is a 'pit' that needs to be filled. The increment x = power[i-1] - power[i]. Sum all x values to get the final answer.