1355: [Baltic2009]Radio Transmission

#include<cstdio>
#include<cstring>
using namespace std;
const int N=1e6+5;
char s1[N];int l1,fail[N];
void get_next(){
    int p=0;fail[1]=0;
    for(int i=2;i<=l1;i++){
        while(p>0&&s1[i]!=s1[p+1]) p=fail[p];
        if(s1[i]==s1[p+1]) p++;
        fail[i]=p;
    }
}
int main(){
    scanf("%d",&l1);
    scanf("%s",s1+1);
    get_next();
    printf("%d",l1-fail[l1]);
    return 0;
}

#include<cstdio>
#include<cstring>
using namespace std;
const int N=1e6+5;
typedef long long i64;
i64 p,P,hash_key[N];
char s[N];int n;
inline void get_s_key(){
    hash_key[0]=0;
    for(int i=1;i<=n;i++) hash_key[i]=hash_key[i-1]*P+s[i]-‘A‘;
}
inline i64 query(int x,int y,i64 p){
    return hash_key[y]-hash_key[x-1]*p;
}
int main(){
    P=29;
    scanf("%d",&n);
    scanf("%s",s+1);
    get_s_key();
    p=1;
    for(int L=1;L<=n;L++){
        p*=P;
        bool flag=1;
        for(int i=L+1;i<=n/L*L;i+=L){
            if(query(i,i+L-1,p)!=hash_key[L]){
                flag=0;break;
            }
        }
        if(!flag) continue;
        for(int i=n/L*L+1;i<=n;i++){
            if(s[i]!=s[i-n/L*L]){
                flag=0;break;
            }
        }
        if(!flag) continue;
        printf("%d\n",L);
        break;
    }
    return 0;
}