HDU- 1005 Number Sequence(矩阵快速幂)

矩阵快速幂裸题·····

 

#include <cstdio>
#include <iostream>
#include <algorithm>
#define modd            7
using namespace std;
struct matrix
{
    int m[2][2];
};
int a, b, n;
matrix cash(matrix a,matrix b){
    matrix tem;
    for (int i = 0; i < 2 ; ++i)
    {
        for (int j = 0; j < 2 ; ++j)
        {
            tem.m[i][j] = 0;
            for (int k = 0; k < 2; ++k)
                tem.m[i][j] += (a.m[i][k]*b.m[k][j])%modd;
        }
    }
    return tem;
}
int ma_pow(int n){
    matrix ans, muti;
    ans.m[0][0] = (((a+b)*a)%modd+b)%modd ;ans.m[0][1] = (a+b)%modd; 
    ans.m[1][0] = 1;
    ans.m[1][1] = 1;
    muti.m[0][0] = a;muti.m[0][1] = 1;muti.m[1][0] = b;muti.m[1][1] = 0;
    while(n){
        if(n&1)
            ans = cash(ans,muti);
        muti = cash(muti,muti);
        n>>=1;
    }
    return ans.m[1][1]%modd;
}
int main(int argc, char const *argv[])
{
      while(~scanf("%d%d%d",&a,&b ,&n) && n != 0)
        printf("%d\n", ma_pow(n-1));
    return 0;
    
    return 0;
}