POJ-1961-Period

#include <stdio.h>
#include <string.h>
using namespace std;
const int maxn=1000001;
char a[maxn];
char b[maxn];
int  n[maxn];
int len,len1;
void get_next()
{
    int i=0;
    int j=-1;
    n[0]=-1;
    while(i<len)
    {
        if(j==-1||a[i]==a[j])
        {
            i++;
            j++;
            n[i]=j;
        }
        else
            j=n[j];
    }
}
int main()
{
    int q=1;
    while(scanf("%d",&len)!=EOF&&len)
    {
        memset(n,0,sizeof(n));
            scanf("%s",a);
        get_next();
        printf("Test case #%d\n",q++);
        for(int i=2;i<=len;i++)
        {
            if(i%(i-n[i])==0&&n[i])
            {
                printf("%d %d\n",i,i/(i-n[i]));
            }
        }
        printf("\n");
    }
    return 0;
}