51nod1126(矩阵快速幂)

题目链接：https://www.51nod.com/onlineJudge/questionCode.html#!problemId=1126

题意：中文题诶～

思路：构造矩阵：

　　

（ 0, 1 )^n-1    *    ( f0, f1 )

( b, a )                 ( f1, f2 )

代码：

 #include <bits/stdc++.h>
 #define mod 7
 #define MAXN 2
 using namespace std;

 struct Matrix{
     int gg[MAXN][MAXN];
 };

 Matrix x;
 Matrix temp={, , , };
 Matrix ans={, , , };

 Matrix multi(Matrix a, Matrix b){
     Matrix c;
     memset(c.gg, , sizeof(c.gg));
     for(int i=; i<MAXN; i++){
         for(int j=; j<MAXN; j++){
             for(int k=; k<MAXN; k++){
                 c.gg[i][j]+=a.gg[i][k]*b.gg[k][j]%mod;
             }
             c.gg[i][j]=(c.gg[i][j]+mod)%mod;
         }
     }
     return c;
 }

 int get_pow(int n){
     while(n){
         if(n&){
             ans=multi(ans, x);
         }
         x=multi(x, x);
         n>>=;
     }
     ans=multi(ans, temp);
     return (ans.gg[][]%mod+mod)%mod;
 }

 int main(void){
     int a, b, n;
     cin >> a >> b >> n;
     x.gg[][]=, x.gg[][]=, x.gg[][]=b, x.gg[][]=a;
     cout << get_pow(n-) << endl;
 }