KMP中next[ ]数组有一个性质:

若一个字符串s[ ]为循环串时（例如abcabcabc）,那么它的next[ ]数组满足下列性质:

1.len%(len-p[len])==0   

2.len/(len-p[len]) 就是该字符串的循环次数   //注意 该题目中若len/(len-p[len])==1,则非循环串,不可取

for(i=2;i<=n;i++){
    if(i%(i-s[i])==0&&i/(i-p[i])!=1){
    
    
    }
}

 代码

#include "iostream"
#include "algorithm"
#include "cstring"
#include "iomanip"
#include "stdio.h"
using namespace std;
char s[1000005];
int nextt[1000005];
void getnext(int n){
    int i=0,j=-1;
    nextt[0]=-1;
    while(i<n){
        if(j==-1||s[i]==s[j]){
            i++;
            j++;
            nextt[i]=j;
        }
        else j=nextt[j];
    }
}

int main(){
    int n,t=0;
    std::ios::sync_with_stdio(false);
    while(cin>>n&&n!=0){
        memset(s,0,sizeof(s));
        cin>>s;
        printf("Test case #%d\n",++t);
        getnext(n);
        for(int i=2;i<=n;i++){
            if(i%(i-nextt[i])==0&&i/(i-nextt[i])!=1)
                printf("%d %d\n",i,i/(i-nextt[i]));
        }   
        printf("\n");
    }
    return 0;
}