"Leetcode" 459. Repeated Substring Pattern

Given a non-empty string check if it can be constructed by taking a substring of it and appending multiple copies of the S Ubstring together. Assume the given string consists of lowercase Chinese letters only and its length would not exceed 10000.

Example 1:

Input: "Abab" Output:TrueExplanation:It ' s the substring "AB" twice.

Example 2:

Input: "ABA" Output:false

Example 3:

Input: "Abcabcabcabc" Output:TrueExplanation:It ' s The substring "abc" four times. (and the substring "ABCABC" twice.)

Test instructions

See if a string can be repeated by a substring, return true if possible, or return false

Ideas:

Change the scanning step, double cycle

1. Assume that a string of length p can be repeated, 1=<p<=len (s)

2. Repeat multiple loops, verifying str[i]! in each cycle =str[i+p], if true, break;

3. If one can scan to the end, that is i+p=l, and i%p==0, then return to the True

1 BOOLRepeatedsubstringpattern (Char*str) {2     intp,i;3     intL=strlen (str);4     intflag=0;5      for(p=1;p <=l/2;p + +)6     {7          for(i=0; i<l-p;i++)8         {9flag=0;Ten             if(str[i]!=str[i+p]) One                 { Aflag=1; -                      Break; -                 } the         } -         if(0==flag&&i%p==0) -             return true; -     } +     return false; -}

The time complexity of this solution is O (n^2), there is a KMP algorithm, the time complexity of O (n), I have not done, to be supplemented by

"Leetcode" 459. Repeated Substring Pattern