广工赛-hdu6470矩阵快速幂

递推时把(n+1)^3拆开 构造矩阵即可

#include<bits/stdc++.h>
using namespace std;
#define ll long long 
#define mod 123456789
struct Mat{
    ll m[10][10];
    Mat(){memset(m,0,sizeof m);}
}A; 
ll n,F[13];
void mul(Mat A,ll F[13]){
    ll B[13]={};
    for(int i=0;i<6;i++)
        for(int j=0;j<6;j++)
            B[i]=(B[i]+A.m[i][j]*F[j]%mod)%mod;
    memcpy(F,B,sizeof B);
}
void mulself(Mat & A,Mat B){
    Mat C;
    for(int i=0;i<6;i++)
        for(int j=0;j<6;j++)
            for(int k=0;k<6;k++)
                C.m[i][j]=(C.m[i][j]+A.m[i][k]*B.m[k][j]%mod)%mod;
    memcpy(A.m,C.m,sizeof C.m);
}
int main(){
    int T;
    cin>>T;    
    while(T--){
        F[0]=2,F[1]=1,F[2]=27,F[3]=9,F[4]=3,F[5]=1; 
        memset(A.m,0,sizeof A.m);
        A.m[1][0]=1;
        A.m[0][0]=1;A.m[0][1]=2;A.m[0][2]=1;
        A.m[2][2]=1;A.m[2][3]=3;A.m[2][4]=3;A.m[2][5]=1;
        A.m[3][3]=1;A.m[3][4]=2;A.m[3][5]=1;
        A.m[4][4]=1;A.m[4][5]=1;
        A.m[5][5]=1;
        cin>>n;
        n-=2;
        while(n){
            if(n%2)
                mul(A,F);
            mulself(A,A);
            n>>=1;
        }
        cout<<F[0]%mod<<'
';
    }    
}