hdu 1358 Period

http://acm.hdu.edu.cn/showproblem.php?pid=1358

KMP

#include <cstdio>
using namespace std;

const int N=1000010;
char s[N];
int fail[N];
void getfail(char *sp)
{
    fail[0]=-1;
    for(int i=1,j=-1;sp[i];i++)
    {
        while(j!=-1 && sp[i]!=sp[j+1]) j=fail[j];
        if(sp[i]==sp[j+1]) j++;
        fail[i]=j;
    }
}
int main()
{
    int n,C=0;
    while(scanf("%d",&n),n)
    {
        printf("Test case #%d\n",++C);
        scanf("%s",s);
        getfail(s);
        for(int i=1;s[i];i++)
            if(fail[i]!=-1 && (i+1)%(i-fail[i])==0) printf("%d %d\n",i+1,(i+1)/(i-fail[i]));
        printf("\n");
    }
    return 0;
}