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Figma·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jul 2026

Summary

Figma Data Engineer interview with a coding screen that was more straightforward than I expected but still had some gotchas worth knowing about.

Questions Asked (1)

Q1

Write a function to validate whether a given string is a valid IPv4 address.

Algorithms & Data Structures
Author's notes

Looked simple enough.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the exact requirements: IPv4 addresses consist of four decimal numbers separated by dots, each between 0 and 255, with no leading zeros unless the number is exactly '0'. Then outline a solution that splits the string by '.', checks for exactly four parts, and validates each part as a numeric string within range and without leading zeros. Finally, discuss edge cases and test your solution with examples.

Pro tip: Mention that you would avoid using regular expressions for this problem because they can be error-prone and less readable; instead, a straightforward split-and-validate approach is clearer and easier to maintain. Also, explicitly state that you would handle edge cases like empty strings, extra dots, and non-numeric characters.

1. Clarify requirements and edge cases

Ask if the input can contain leading/trailing spaces, if leading zeros are allowed (e.g., '01'), and if the function should return a boolean or throw an error. Confirm that only decimal digits and dots are allowed.

2. Split the string by dots

Use the split method to divide the string into parts based on the dot character. Check that the resulting array has exactly four elements.

3. Validate each part

For each part, ensure it is a non-empty string of digits, does not have leading zeros (unless it is '0'), and its integer value is between 0 and 255 inclusive.

4. Return the result and test

If all parts pass validation, return true; otherwise, return false. Walk through a few test cases (valid, invalid, edge cases) to verify correctness.

Key Points to Mention

  • Exactly four parts separated by dots.
  • Each part must be a decimal number between 0 and 255.
  • No leading zeros allowed unless the part is exactly '0'.
  • Only digits and dots are allowed; no other characters.
  • Handle edge cases: empty string, extra dots, parts with non-digit characters, parts out of range.
  • Time complexity is O(n) where n is the length of the string; space complexity is O(1) if not counting the split array.

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