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：
1 #include <bits/stdc++.h>
2 #define mod 7
3 #define MAXN 2
4 using namespace std;
5
6 struct Matrix{
7 int gg[MAXN][MAXN];
8 };
9
10 Matrix x;
11 Matrix temp={0, 1, 1, 1};
12 Matrix ans={1, 0, 0, 1};
13
14 Matrix multi(Matrix a, Matrix b){
15 Matrix c;
16 memset(c.gg, 0, sizeof(c.gg));
17 for(int i=0; i<MAXN; i++){
18 for(int j=0; j<MAXN; j++){
19 for(int k=0; k<MAXN; k++){
20 c.gg[i][j]+=a.gg[i][k]*b.gg[k][j]%mod;
21 }
22 c.gg[i][j]=(c.gg[i][j]+mod)%mod;
23 }
24 }
25 return c;
26 }
27
28 int get_pow(int n){
29 while(n){
30 if(n&1){
31 ans=multi(ans, x);
32 }
33 x=multi(x, x);
34 n>>=1;
35 }
36 ans=multi(ans, temp);
37 return (ans.gg[0][1]%mod+mod)%mod;
38 }
39
40 int main(void){
41 int a, b, n;
42 cin >> a >> b >> n;
43 x.gg[0][0]=0, x.gg[0][1]=1, x.gg[1][0]=b, x.gg[1][1]=a;
44 cout << get_pow(n-1) << endl;
45 }