[Bzoj1009]GT考试（KMP）（矩乘优化DP）

# include <iostream>
# include <cstdio>
# include <cstring>
using namespace std;
int fail[23][11],n,m,mod,next[23]; 
struct fi{
    int data[23][23];
}A,T;
char str[23];
void get_Fail(){
    scanf("%s",str);
    for(int i = 1,j = 0;i < m;i++){
        while(j && str[i] != str[j])j = next[j - 1];
        if(str[i] == str[j])j++;
        next[i] = j;
    }
    memset(T.data,0,sizeof T);
    for(int i = 0;i < m;i++){
        for(int j = 0;j <= 9;j++){
            int k = i;
            while(k && str[k] - ‘0‘ != j)k = next[k - 1];
            if(j == str[k] - ‘0‘)T.data[i][k + 1]++;
            else T.data[i][0]++;
        }
    }
    memset(A.data,0,sizeof A.data);
    for(int i = 0;i < m;i++)A.data[i][i] = 1;
}
fi operator * (const fi & c,const fi & d){
    fi t;
    for(int i = 0;i < m;i++){
        for(int j = 0;j < m;j++){
            t.data[i][j] = 0;
            for(int k = 0;k < m;k++){
                (t.data[i][j] += c.data[i][k] * d.data[k][j]) %= mod;
            }
        }
    }
    return t;
}
void cmd(int k){
    while(k){
        if(k & 1)A = A * T;
        k >>= 1;
        T = T * T;
    }
}
int main(){
    scanf("%d %d %d",&n,&m,&mod);
    get_Fail();
    cmd(n);
    int ans = 0;
    for(int i = 0;i < m;i++)(ans += A.data[0][i]) %= mod;
    printf("%d\n",ans);
    
}