The Minimum Length - HUST 1010（求最小循环节）

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

const int MAXN = 1e6+7;
const int oo = 1e9+7;

char s[MAXN];
int next[MAXN];

void GetNext(int N)
{
    int i=0, j=-1;
    next[0] = -1;

    while(i < N)
    {
        if(j==-1 || s[i]==s[j])
            next[++i] = ++j;
        else
            j = next[j];
    }
}

int main()
{

    while(scanf("%s", s) != EOF)
    {
        int N = strlen(s);

        GetNext(N);

        printf("%d\n", N-next[N]);
    }

    return 0;
}