hdu 5171 GTY's birthday gift (构造矩阵)

#include<iostream>
#include<math.h>
#include<stdio.h>
#include<algorithm>
#include<string.h>
#include<vector>
#include<queue>
#include<map>
#include<set>
using namespace std;
#define B(x) (1<<(x))
typedef long long ll;
const int oo=0x3f3f3f3f;
const ll OO=1LL<<61;
const ll MOD=10000007;
const int maxn=2;
int n;
int val[100005];

struct Matrix
{
    ll maze[3][3];

    friend Matrix operator*(Matrix a,Matrix b)
    {
        Matrix c;
        memset(c.maze,0,sizeof c.maze);
        for(int i=0;i<3;i++)
            for(int j=0;j<3;j++)
                for(int k=0;k<3;k++)
                    c.maze[i][j]=(c.maze[i][j]+a.maze[i][k]*b.maze[k][j]+MOD)%MOD;
        return c;
    }
    friend Matrix operator^(Matrix a,ll k)
    {
        Matrix c;

        for(int i=0;i<3;i++)
            for(int j=0;j<3;j++)
                c.maze[i][j]=(i==j);

        while(k)
        {
            if(k&1)
                c=c*a;
            a=a*a;
            k>>=1;
        }
        return c;
    }
};

int main()
{
    int a,b;
    ll k,sum;
    Matrix A;
    A.maze[0][0]=1;A.maze[0][1]=1;A.maze[0][2]=1;
    A.maze[1][0]=0;A.maze[1][1]=1;A.maze[1][2]=1;
    A.maze[2][0]=0;A.maze[2][1]=1;A.maze[2][2]=0;
    while(scanf("%d %I64d",&n,&k)!=EOF)
    {
        sum=0;
        for(int i=1;i<=n;i++)
            scanf("%d",&val[i]);
        sort(val+1,val+1+n);
        for(int i=1;i<=n-2;i++)
            sum=(sum+val[i]+MOD)%MOD;
        a=val
;
        b=val[n-1];
        ///接下来是矩阵快速幂
        Matrix F1;
        memset(F1.maze,0,sizeof F1.maze);
        F1.maze[0][0]=a+b;
        F1.maze[1][0]=a;
        F1.maze[2][0]=b;
        Matrix ans=(A^k)*F1;
        cout<<(ans.maze[0][0]+sum+MOD)%MOD<<endl;
    }
    return 0;
}