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Early-stage Startup·Software Engineer·Technical Phone Screen·Junior

JuniorPrefer not to say
May 2026

Summary

Spent way too long prepping advanced data structures and got asked to reverse a string with some vowel-skipping logic. Brain completely left the building.

Questions Asked (1)

Q1

Reverse a string while leaving vowels in their original positions.

Algorithms & Data Structures
Author's notes

I froze.

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AI HintsAI Generated

Suggested Approach

First, clarify the problem: reverse the string but keep vowels in their original indices. Then, extract the consonants, reverse them, and place them back into the original string at consonant positions, leaving vowels untouched. Finally, test with edge cases like empty strings, all vowels, and mixed cases.

Pro tip: Discuss time and space complexity upfront: O(n) time and O(n) space, and mention that you can optimize space by using two pointers to swap consonants in-place if the string is mutable. This shows awareness of efficiency and adaptability.

1. Clarify the problem

Confirm that vowels (a, e, i, o, u, and sometimes y) should remain in their original positions, and only consonants are reversed. Ask about case sensitivity and whether 'y' is considered a vowel.

2. Plan the approach

Decide on an algorithm: either extract consonants, reverse them, and rebuild the string, or use two pointers to swap consonants in-place. Consider time and space complexity.

3. Implement the solution

Write clean code with meaningful variable names. Handle edge cases such as empty strings, strings with no consonants, and strings with all consonants.

4. Test with examples

Walk through test cases: 'hello' -> 'holle', 'leetcode' -> 'letcedoe', 'a' -> 'a', 'bcdf' -> 'fdcb'. Verify vowels remain in place.

5. Analyze complexity and optimize

State time complexity O(n) and space complexity O(n) for the extraction method. If using two pointers, space can be O(1) for mutable strings. Discuss trade-offs.

Key Points to Mention

  • Definition of vowels and handling of 'y' (clarify with interviewer).
  • Two-pointer technique for in-place reversal of consonants.
  • Time and space complexity analysis (O(n) time, O(n) or O(1) space).
  • Edge cases: empty string, all vowels, all consonants, mixed case.
  • String immutability in languages like Java/Python and how it affects in-place approaches.
  • Clean code practices: modular functions, descriptive variable names, and comments.

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