Break a Palindrome

MediumGreedygreedy

Solve this the way you would in the interview: out loud, on a timer, with an AI interviewer asking follow-ups while you code. You get a scored report at the end.

Practice this as a mock interviewFree to start, no account needed

Problem

You are given a palindrome palindrome of lowercase letters. Change exactly one character to a different lowercase letter so that the result is not a palindrome, and among all such results choose the lexicographically smallest. Return that string, or the empty string "" if no single change can break the palindrome.

Examples

Input: palindrome = "abccba"
Output: "aaccba"
Changing the first `b` to `a` gives the smallest non-palindrome.
Input: palindrome = "a"
Output: ""
A one-letter string is always a palindrome, whatever the letter.

Constraints

  • 1 <= palindrome.length <= 1000
  • palindrome consists of lowercase English letters and reads the same backward

What the interviewer grades

A correct solution is one of five scores. The report also grades problem understanding (did you clarify inputs and edge cases before coding), problem solving, communication while you work, code quality, and testing. See a sample report, or read up on the pattern in the lessons.

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