Educational Codeforces Round 13 D. Iterated Linear Function (矩阵快速幂)

题目链接：http://codeforces.com/problemset/problem/678/D

简单的矩阵快速幂模版题

矩阵是这样的：

 #include <bits/stdc++.h>
 using namespace std;
 typedef __int64 LL;
 struct data {
     LL mat[][];
 };
 LL mod = 1e9 + ;

 data operator *(data a , data b) {
     data res;
     for(int i =  ; i <=  ; ++i) {
         for(int j =  ; j <=  ; ++j) {
             res.mat[i][j] = ;
             for(int k =  ; k <=  ; ++k) {
                 res.mat[i][j] = (a.mat[i][k] * b.mat[k][j] % mod + res.mat[i][j]) % mod;
             }
         }
     }
     return res;
 }

 data operator ^(data a , LL n) {
     data res;
     for(int i =  ; i <=  ; ++i) {
         for(int j =  ; j <=  ; ++j) {
             res.mat[i][j] = i == j;
         }
     }
     while(n) {
         if(n & )
             res = res * a;
         a = a * a;
         n >>= ;
     }
     return res;
 }

 int main()
 {
     LL a , b , n , x;
     cin >> a >> b >> n >> x;
     data temp , res;
     temp.mat[][] = a % mod , temp.mat[][] =  , temp.mat[][] = b % mod, temp.mat[][] = ;
     res.mat[][] = x % mod , res.mat[][] =  , res.mat[][] = res.mat[][] = ;
     temp = temp ^ n;
     res = res * temp;
     cout << res.mat[][] << endl;
     return ;
 }