判断某个字符串能否由某个字串重复若干次组成

题目：

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.)

解题思路：

分成k*i个子序列，然后依次判断。

# include<stdio.h>
# include<string.h>

int main()
{
	char str[30];
	int i=0,j=0,l=0;
	
	while(~scanf("%s",str))
	{
		bool flag=false;
		int len=strlen(str);
		int n=len/2;
		
		for(i=n;i>=1;i--)
		{
			if(len%i==0)
			{
				int cnt=0;
				flag=false;
				int k=len/i;//k个子序列，每个序列长i
				for(l=1;l<k;l++)
				{
					for(j=0;j<i;j++)
					{
						if(str[j]==str[l*i+j])
						{
							cnt++;
						}	
					}
				}
				
				if(cnt==(k-1)*i)
				{
					flag=true;
					break;
				}
			}
		}
		
		if(flag==true)
			printf("True\n");
		else
			printf("False\n");

	}
	
	return 0;
}