poj 1961 Period

#include <iostream>        //KMP算法,参考poj 2406 Power Strings
using namespace std;
char B[2000000];    
int m,next[2000000];        
void get_next()
{
    next[1]=0;
    int j=0;
    for(int i=2;i<=m;++i)
    {
        while(j>0&&B[j+1]!=B[i])
            j=next[j];
        if(B[j+1]==B[i])
            j=j+1;
        next[i]=j;
    }
}
int main()
{
    int num=1;
    while(scanf("%d",&m)&&m)
    {
        scanf("%s",B+1);
        get_next();
        printf("Test case #%d\n",num++);
        for(int i=2;i<=m;++i)
            if(next[i]>0&&i%(i-next[i])==0)
                printf("%d %d\n",i,i/(i-next[i]));
        printf("\n");
    }
    return 0;
}