Meta·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say

Jun 2026Remote

Summary

Meta SWE coding round, one question the whole time. Pretty standard algorithmic problem but the O(1) space constraint is where they actually want to see if you know what you're doing.

Questions Asked (1)

Given a string, determine whether you can make it a palindrome by removing at most one character. Return true or false.

Algorithms & Data Structures

Author's notes

I jumped straight to the two-pointer approach which felt right, but I fumbled on the part where the pointers mismatch.

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AI HintsAI Generated

Suggested Approach

Use a two-pointer technique from both ends, and when a mismatch occurs, check if skipping either the left or right character results in a palindrome. This ensures O(n) time and O(1) space, which is optimal for this problem.

Pro tip: Clarify that 'removing at most one character' includes removing zero characters, so the original string being a palindrome should return true. Also, mention that the two-pointer approach is optimal and avoids unnecessary string manipulation.

1. Clarify the problem

Confirm that removing zero or one character is allowed, and that the string can contain any characters. Ask if the input can be empty or have length 1, which are trivially palindromes.

2. Use two pointers

Initialize left and right pointers at the start and end of the string. Move them inward while characters match.

3. Handle mismatch

When a mismatch occurs, check if the substring skipping the left character or skipping the right character is a palindrome. If either is, return true.

4. Return result

If no mismatch is found, the string is already a palindrome, so return true. If both skip options fail, return false.

5. Analyze complexity

State that the time complexity is O(n) because each character is visited at most twice, and space complexity is O(1) as no extra data structures are used.

Key Points to Mention

Two-pointer technique for efficient palindrome checking
Handling the mismatch by checking both possible removals
Time complexity O(n) and space complexity O(1)
Edge cases: empty string, single character, already palindrome
Avoiding string slicing to maintain O(1) space
The problem is equivalent to checking if the string can be a palindrome with at most one deletion

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