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Asana·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say
Jun 2026

Summary

Coding round at Asana centered on an ASCII art rendering problem. The core question was straightforward enough but the follow-ups kept coming and that's where things got interesting.

Questions Asked (1)

Q1

Given a fixed-height ASCII art character set, render an input string by concatenating each character's block side by side, line by line.

Algorithms & Data StructuresTechnical Trade-offsSystem Design
Author's notes

The base case clicked pretty fast.

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AI HintsAI Generated

Suggested Approach

Clarify the input format and constraints, then propose a line-by-line concatenation approach using a mapping from characters to their ASCII art blocks. Discuss time and space complexity, and consider edge cases like unknown characters and empty input.

Pro tip: Mention that you would preprocess the character set into a dictionary for O(1) lookups, and that you would handle unknown characters gracefully (e.g., by using a placeholder or skipping) to avoid crashes in production.

1. Clarify requirements and constraints

Ask about the exact format of the ASCII art character set (e.g., array of strings per character), the expected output (e.g., list of strings or single string with newlines), and any constraints on input size or character set.

2. Design the data structure

Propose storing the character set in a hash map where each character maps to its list of lines (or a 2D array). This allows efficient lookup and easy iteration over lines.

3. Outline the algorithm

For each line index from 0 to height-1, iterate through the input string, look up each character's line, and concatenate them. Collect these lines into the final output.

4. Analyze complexity and edge cases

State that time complexity is O(n * h) where n is input length and h is height, and space is O(n * h) for output. Discuss handling of unknown characters, empty string, and very long inputs.

5. Discuss trade-offs and optimizations

Mention possible optimizations like precomputing the entire output as a single string with newlines, or using a StringBuilder for efficiency. Also consider if the character set is fixed and small, an array indexed by ASCII value could be faster.

Key Points to Mention

  • Mapping characters to their ASCII art blocks using a dictionary for O(1) access.
  • Line-by-line concatenation: outer loop over height, inner loop over input characters.
  • Time complexity O(n * h) and space complexity O(n * h) for output.
  • Handling unknown characters (e.g., default block or error handling).
  • Edge cases: empty input, input with spaces, and characters not in the set.
  • Potential optimizations: using StringBuilder, precomputing output, or array-based lookup for fixed ASCII set.

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