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Armada·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jun 2026

Summary

Coding screen at Armada for a software engineer role. Pretty straightforward problem but the follow-up one-liner twist is where things got interesting.

Questions Asked (1)

Q1

Given two integers Count and col_num, print a matrix of consecutive integers from 0 to Count-1 line by line, where each line is prefixed by its starting index and contains col_num values. Handle the case where Count is not evenly divisible by col_num. Follow-up: rewrite it as a one-liner.

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

The base version wasn't bad.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem: confirm that each line is prefixed by its starting index (0, col_num, 2*col_num, ...) and that the last line may have fewer than col_num values. Then present a clean loop-based solution that slices the range 0..Count-1 into chunks of size col_num, handling the remainder naturally. For the follow-up, show a one-liner using list comprehension with slicing, and briefly discuss readability trade-offs.

Pro tip: Mention that the prefix is the starting index of each row, not the row number, and that the last row may be shorter—this shows you read the spec carefully. For the one-liner, use a list comprehension with range and slicing, and note that while concise, it may sacrifice clarity for maintainability.

1. Clarify requirements and edge cases

Confirm the meaning of 'prefixed by its starting index' and how to handle the last incomplete row. Ask about output format (e.g., printed lines vs. returned list of lists) and whether Count can be zero or negative.

2. Design the chunking logic

Use a loop over range(0, Count, col_num) to generate starting indices. For each index i, take the slice from i to min(i+col_num, Count) to handle the remainder.

3. Implement the multi-line solution

Write a function that iterates, builds each row as [i] + list(range(i, min(i+col_num, Count))), and prints or collects the rows. Ensure the last row is shorter if Count % col_num != 0.

4. Derive the one-liner

Express the same logic as a list comprehension: [[i] + list(range(i, min(i+col_num, Count))) for i in range(0, Count, col_num)]. Optionally, use a lambda or print inside a comprehension for direct output.

5. Discuss trade-offs and test

Compare readability, performance, and maintainability of the loop vs. one-liner. Walk through test cases: Count=10, col_num=3; Count=0; Count < col_num; and Count divisible by col_num.

Key Points to Mention

  • Use of range with step col_num to generate starting indices efficiently.
  • Slicing with min(i+col_num, Count) to avoid index out of range and handle the remainder.
  • The prefix is the starting index (0, col_num, 2*col_num, ...), not the row number.
  • One-liner via list comprehension, noting potential readability concerns.
  • Edge cases: Count=0, Count < col_num, and Count not divisible by col_num.
  • Time complexity O(Count) and space O(Count) for output, which is optimal.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.