1227. Repeated Substring Pattern

描述

Given a non-empty string check if it can be constructed by taking a substring of it and appending multiple copies of the substring together. You may assume the given string consists of lowercase English letters only and its length will not exceed 10000.

Example 1:

Input: "abab"

Output: True

Explanation: It's the substring "ab" twice.

Example 2:

Input: "aba"

Output: False

Example 3:

Input: "abcabcabcabc"

Output: True

Explanation: It's the substring "abc" four times. (And the substring "abcabc" twice.)

我起初用的是关联容器，想直接算每个字母的出现次数，但很明显这是错误的做法，它是要求连续子串。

参考博客：http://www.cnblogs.com/grandyang/p/6087347.html

所以采用遍历的办法，从长度为1 长度为一半的子字符串。

class Solution {
public:
    /**
     * @param s: a string
     * @return: return a boolean
     */
    bool repeatedSubstringPattern(string &s) {
        // write your code here
        int n=s.size();
        for(int i=n/2;i>0;--i){
            if(n%i==0){
                int c=n/i;
                string t="";
                for(int j=0;j<c;++j) t+=s.substr(0,i);
                if (t == s) return true;
            }
        }
        return false;
    }
};