459. Repeated Substring Pattern
Given a string s, check if it can be constructed by taking a substring of it and appending multiple copies of the substring together.
Examples
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 <= 104s consists of lowercase English letters.