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Meta·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

Meta SWE interview with a classic palindrome check question. Not much to report, pretty standard coding screen.

Questions Asked (1)

Q1

Determine whether a given string is a valid palindrome.

Algorithms & Data Structures
Author's notes

Pretty bread and butter as far as coding questions go.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the definition of a valid palindrome (e.g., case sensitivity, alphanumeric only) and then propose a two-pointer approach that compares characters from both ends moving inward. Discuss time and space complexity, and mention alternative approaches like reversing the string or using recursion.

Pro tip: Always clarify edge cases and constraints before coding; this shows attention to detail and prevents incorrect assumptions. Also, mention that you can optimize space by using two pointers instead of creating a reversed copy.

1. Clarify requirements

Ask about input constraints: case sensitivity, handling of non-alphanumeric characters, and whether the string can be empty. Confirm the definition of a valid palindrome.

2. Discuss approaches

Outline multiple solutions: two-pointer technique, reversing the string, or using a stack. Compare their time and space complexities.

3. Choose optimal solution

Select the two-pointer approach for O(n) time and O(1) space, explaining why it's efficient and handles the problem well.

4. Walk through example

Trace the algorithm on a sample input, such as 'A man, a plan, a canal: Panama', to demonstrate correctness and edge case handling.

5. Analyze complexity and edge cases

State time and space complexity, and discuss edge cases like empty string, single character, or strings with only non-alphanumeric characters.

Key Points to Mention

  • Two-pointer technique: left and right pointers moving inward
  • Time complexity O(n) and space complexity O(1) for two-pointer approach
  • Handling non-alphanumeric characters and case insensitivity (e.g., using Character.isLetterOrDigit and toLowerCase)
  • Alternative approaches: reversing the string (O(n) space) or recursion (O(n) stack space)
  • Edge cases: empty string, single character, strings with no alphanumeric characters
  • Clarifying questions to ask the interviewer about input constraints

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