poj 2406 Power Strings

求解字符串是否是周期串，如果是输出循环了几次。KMP周期问题，循环节是i - next[i]。

代码：

#include <stdio.h>      #include <string.h>  #include <iostream>  #include <algorithm>        using namespace std;        const int MAX = 1000010;char s[MAX];int n,f[MAX];void getf(){f[0] = f[1] = 0;for(int i=1; i<n; i++){int j = f[i];while(j && s[i] != s[j]) j = f[j];f[i+1] = s[i] == s[j] ? j + 1 : 0;}}int main(){while(scanf("%s",s) == 1 && s[0] != '.'){n = strlen(s);getf();if(f[n] && n % (n - f[n]) == 0) cout << n / (n - f[n]) << endl;else puts("1");}return 0;}