hdu 1358 Period

http://acm.hdu.edu.cn/showproblem.php?pid=1358

寻找循环性前缀，利用KMP周期性。

AC代码：

#include <stdio.h>#include <string.h>#include <iostream>#include <algorithm>using namespace std;const int MAX = 1000010;char str[MAX];int next[MAX];void getnext(){    int i=0, j=-1,n=strlen(str);    next[0] = -1;    while(i < n){        if(j == -1 || str[i] == str[j]){            i++,j++;            next[i] = j;        }        else j = next[j];    }}int main(){    int n,t = 0;    while(scanf("%d",&n) == 1){        if(!n) break;        scanf("%s",str);        getnext();        printf("Test case #%d\n",++t);        for(int i=1; i<=n; i++){            int count = i - next[i];            if(count != i && i % count == 0)                printf("%d %d\n",i,i/count);        }        printf("\n");    }    //system("pause");    return 0;}