POJ1961 Period

同UVa 1328

http://www.cnblogs.com/SilverNebula/p/5550595.html

写一半才想起来这题以前做过……

 

kmp求循环节

/*by SilverN*/
#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdio>
#include<cmath>
using namespace std;
const int mxn=1000200;
char s[mxn];
int next[mxn];
int n;
int main(){
    int i,j;
    int cas=0;
    while(scanf("%d",&n) && n){
        printf("Test case #%d\n",++cas);
        scanf("%s",&s);
        next[0]=0;
        next[1]=0;
        j=0;
        for(i=1;i<n;i++){
            j=next[i];
            while(s[j]!=s[i] && j)j=next[j];
            if(s[j]==s[i])j++;
            next[i+1]=j;
        }
        for(i=2;i<=n;i++){
            if(next[i] && i%(i-next[i])==0)
                printf("%d %d\n",i,i/(i-next[i]));
        }
        printf("\n");
    }
    return 0;
}