0459 - Repeated Substring Pattern

Description (leetcode)

Given a string s, check if it can be constructed by taking a substring of it and appending multiple copies of the substring together.

Example 1:

Input: s = “abab”

Output: true

Explanation: It is the substring “ab” twice.

Example 2:

Input: s = “aba”

Output: false

Example 3:

Input: s = “abcabcabcabc”

Output: true

Explanation: It is the substring “abc” four times or the substring “abcabc” twice.

Constraints:

• 1 <= s.length <= 10⁴
• s consists of lowercase English letters.

submission

impl Solution {
    // see: https://leetcode.com/problems/repeated-substring-pattern/discuss/826135/C%2B%2B-O(N)-time-or-One-liner-without-KMP-Explained-or-Beats-99
    pub fn repeated_substring_pattern(s: String) -> bool {
        s.repeat(2)[1..s.len() * 2 - 1].contains(&s)
    }
}