POJ - 2406 - Power Strings （字符串求周期--next函数的妙用）

题目传送：POJ - 2406

思路：就是利用kmp中next数组的特性来求最大周期的

AC代码：

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

const int maxn = 1000005;
char s[maxn];
int next[maxn];

int main() {
	while(scanf("%s", s) != EOF) {
		if(s[0] == '.') break;

		next[0] = -1;
		int len = strlen(s);
		int i = 0, j = -1;
		while(i < len) {
			if(j == -1 || s[i] == s[j]) next[++ i] = ++ j;
			else j = next[j];
		}

		if(len % (len - next[len]) == 0) printf("%d\n", len / (len - next[len]));
		else printf("1\n");
	}
	return 0;
}