学步园

next 数组

#include <cstdio>
#include <cstring>
#include <iostream>
#include <time.h>
#include <cstdlib>
#include <cmath>
#include <algorithm>
using namespace std;
int const MOD = 10007;
int const MAXN = 200010;
char s[MAXN];
int next[MAXN],dp[MAXN];
inline void Get_Next(int n){
    memset(next,0,sizeof(next));
    for(int i = 1;i < n;i++){
        int j = next[i];
        while(j && s[i] != s[j]) j = next[j];
        if(s[i] == s[j]) next[i + 1] = j + 1;
        else next[i + 1] = 0;
    }
}
int main(){
    int T;
    while(~scanf("%d",&T)){
        while(T--){
            int n;
            scanf("%d",&n);
            scanf("%s",s);
            Get_Next(n);
            for(int i = 0;i < n;i++){
                dp[i] = 1;
            }
            dp[0] = 0;
            int sum = 0;
            for(int i = 1;i <= n;i++){
                dp[i] = dp[next[i]] + 1;
                sum = (sum + dp[i]) % MOD;
            }
            printf("%d\n",sum);
        }
    }
    return 0;
}