Repeated Substring Pattern

EasyStringshashing

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

Given a string s, decide whether it can be built by writing some shorter substring two or more times back to back. Return true if such a substring exists and false otherwise. A single-character string can never qualify, since the piece must repeat at least twice.

Examples

Input: s = "abab"
Output: true
"ab" written twice.
Input: s = "aba"
Output: false
No shorter piece repeats to form "aba".
Input: s = "abcabcabcabc"
Output: true
Both "abc" (x4) and "abcabc" (x2) work.

Constraints

  • 1 <= s.length <= 10^4
  • `s` consists of lowercase English letters

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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