HDU5950

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=5950

解题思路：

　　

AC代码：

#include <cstdio>
#include <cstring>

using namespace std;
typedef long long ll;
const ll mod=2147493647;
struct Matrix{
    ll mat[7][7];
};
Matrix cst={1,2,1,4,6,4,1,
            1,0,0,0,0,0,0,
            0,0,1,4,6,4,1,
            0,0,0,1,3,3,1,
            0,0,0,0,1,2,1,
            0,0,0,0,0,1,1,
            0,0,0,0,0,0,1};
Matrix Multiply(Matrix x,Matrix y){
    Matrix temp;
    memset(temp.mat,0,sizeof(temp.mat));
    for(int i=0;i<7;i++){
        for(int j=0;j<7;j++){
            for(int k=0;k<7;k++){
                temp.mat[i][j]+=(x.mat[i][k]*y.mat[k][j]%mod);
                temp.mat[i][j]%=mod;
            }
        }
    }
    return temp;
}
Matrix Fast_Power(Matrix a,int m){
    Matrix res;
    memset(res.mat,0,sizeof(res.mat));
    for(int i=0;i<7;i++)    res.mat[i][i]=1;
    while(m){
        if(m&1) res=Multiply(res,a);
        m>>=1;
        a=Multiply(a,a);
    }
    return res;
}
int main(){
    int t;
    int N,a,b;
    scanf("%d",&t);
    while(t--){
        scanf("%d%d%d",&N,&a,&b);
        if(N==1)    printf("%d
",a);
        else if(N==2)   printf("%d
",b);
        else{
            Matrix ret=Fast_Power(cst,N-2);
            ll ans=(ret.mat[0][0]*b%mod+ret.mat[0][1]*a%mod+ret.mat[0][2]*16%mod+ret.mat[0][3]*8%mod+ret.mat[0][4]*4%mod+ret.mat[0][5]*2%mod+ret.mat[0][6]%mod)%mod;
            printf("%lld
",ans);
        }
    }

    return 0;
}