HDU 3336

KMP+DP
DP[i]表示以i结尾的字符串包含多少个前缀
那么DP[i]=DP[fail[i]]-1;

#include <iostream>
#include<cstdio>
#include<cstring>
#define N 200005
#define mod 10007
using namespace std;
char str[N];
int fail[N];
int dp[N];
void kmp(int n){
    fail[0]=-1;
    for(int i=1,j=-1;i<n;i++){
        if(j>=0&&str[j+1]!=str[i])
        j=fail[j];
        if(str[j+1]==str[i])
        j++;
        fail[i]=j;
    }
}
int main()
{
    int T,n;
    scanf("%d",&T);
    while(T--){
        scanf("%d",&n);
        scanf("%s",str);
        kmp(n);
        int ans=1;
        dp[0]=1;
        for(int i=1;i<n;i++){
            if(fail[i]==-1)
            dp[i]=1;
            else
            dp[i]=(dp[fail[i]]+1)%mod;
            ans=(ans+dp[i])%mod;
        }
        printf("%d\n",ans);
    }
    return 0;
}