Power Strings-蒲公英云

Power Strings

Description
Given two strings a and b we define ab to be their concatenation. For example, if a = “abc” and b = “def” then ab = “abcdef”. If we think of concatenation as multiplication, exponentiation by a non-negative integer is defined in the normal way: a^0 = “” (the empty string) and a^(n+1) = a*(a^n).
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Input
Each test case is a line of input representing s, a string of printable characters. The length of s will be at least 1 and will not exceed 1 million characters. A line containing a period follows the last test case.

Output
For each s you should print the largest n such that s = a^n for some string a.

Sample
Input
abcd
aaaa
ababab
.
Output
1
4
3
Hint
This problem has huge input, use scanf instead of cin to avoid time limit exceed.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
char a[100010000];//本题测试数据很多，数组记得开大点
int next[10001000];
void getnext(int len)
{
    int i=0,j=-1;
    next[0]=-1;
    while(i<len)
    {
        if(j==-1||a[j]==a[i])
        {
            j++;
            i++;
            next[i]=j;
        }
        else
            j=-1;
    }
}
int main()
{
    while(~scanf("%s",a))
    {
        if(a[0]=='.')
        break;
        else
        {
            int len=strlen(a);
            memset(next,0,sizeof(next));
            getnext(len);
            int n=len-next[len];
            if(n!=len&&len%n==0)
                printf("%d\n",len/n);
            else
                printf("1\n");
        }
    }
}