P4391 [BOI2009]Radio Transmission 无线传输

#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdio>
#include<cmath>
#include<queue>
using namespace std;
char ss[1000610];
int n,kmp[1000610];
int main(){
    scanf("%d%s",&n,ss+1);
    for(int i=2,j=0;i<=n;i++){
        if(j&&ss[i]!=ss[j+1]){j=kmp[j];}
        if(ss[i]==ss[j+1]){j++;} 
        kmp[i]=j;
    }
    printf("%d\n",n-kmp[n]);
    return 0;
}