leetcode 459 Repeated Substring Pattern

Java:

class Solution {
    public boolean repeatedSubstringPattern(String s) {
        int len = s.length();
        for(int i=len/2; i>0; i--){
            if(len%i==0){
                String sub = s.substring(0, i);
                StringBuilder st = new StringBuilder();
                for(int j=0; j<len/i; j++){
                    st.append(sub);
                }
                if(st.toString().equals(s)) return true;
             }
        }
        return false;
    }
}

Python:

class Solution:
    def repeatedSubstringPattern(self, s):
        """
        :type s: str
        :rtype: bool
        """
        return s in (s*2)[1:-1]