UVA10298 POJ2046 Power Strings

Posted 2020-12-13 mogeko

gate

一年前做的.
求一个字符串由多少个循环节构成.
KMP.
结论:若(n \% (n-next[n]) ot= 0)则不是由循环节构成的.
否则,答案为(n/(n-next[n])).

code

#include<cstdio>
#include<iostream>
#include<cmath>
#include<cstring>
#define MogeKo qwq
using namespace std;
#include<string>
const int maxn = 1e6+10;
int n,f[maxn];
char s[maxn];

int main() {
	while(1) {
		scanf("%s",s);
		if(s[0] == ‘.‘)break;
		n = strlen(s);
		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];
			if(s[i] == s[j]) f[i+1] = j+1;
			else f[i+1] = 0;
		}
		if(n%(n-f[n])!=0) printf("1
");
		else printf("%d
",n/(n-f[n]));
	}
	return 0;
}