poj 1961 Period

http://poj.org/problem?id=1961

此题直接上代码：

#include<iostream>

#include<cstdio>

#include<cstring>

#include<string>

#include<cmath>

#include<queue>

#include<algorithm>

#include<set>



using namespace std;



const int N=1000010;



char s[N];

int next[N];

int ans[N];

void findnext(int n)

{

    int j=-1;

    int i=0;

    next[0]=-1;

    while(i<n)

    {

        if(j==-1||s[i]==s[j])

        {

            ++j;++i;next[i]=j;

        }else

        {

            j=next[j];

        }

    }

}

int main()

{



   int n;

   int w=0;

   while(scanf("%d",&n)!=EOF,n)

   {

       ++w;

       getchar();

       gets(s);

       findnext(n);

       printf("Test case #%d\n",w);

       for(int i=2;i<=n;++i)

       {

           int l=i-next[i];

           if(next[i]>=i/2&&i%l==0)

           {

               printf("%d %d\n",i,i/l);

           }

       }

       printf("\n");

   }

   return 0;

}