P4391 无线传输

题面:https://www.luogu.org/problemnew/show/P4391

本题中n-next[n]即为字符串最小长度的循环节。

Code:
#include<cstring>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<algorithm>
#include<ctime>
using namespace std;
const int N=1000005;
int n,nxt[N];
char ss[N];
int main(){
    scanf("%d%s",&n,ss+1);
    int j=0;
    for(int i=2;i<=n;++i){
        if(j&&ss[i]!=ss[j+1]) j=nxt[j];
        if(ss[i]==ss[j+1]) ++j;
        nxt[i]=j;
    }
    printf("%d",n-nxt[n]);
    return 0;
}