POJ1961Period

POJ1961

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int maxn=1000010;
char b[maxn];
int next[maxn];
void prekmp()
{
    int j=-1;next[0]=-1;
    for(int i=1;b[i];++i)
    {
        while(j!=-1&&b[i]!=b[j+1]) j=next[j];
        if(b[i]==b[j+1]) j++;
        next[i]=j;
    }
}
int main()
{
    int n;
    while(scanf("%d",&n)&&n)
    {
        scanf("%s",b);
        prekmp();
        for(int i=1;i<n;++i)
        {
            int len=i+1;
            next[i]++;
            if(len%(len-next[i])==0&&len/(len-next[i])>1) printf("%d %d\n",len,len/(len-next[i]));
        }
    }
    return 0;
}