51Nod 1242 斐波那契数列的第N项（矩阵快速幂）

 #include <iostream>
 #include <algorithm>
 using namespace std;

 typedef long long LL;
 const int maxn = ;
 const LL m = ;

 struct Matrix
 {
     LL v[maxn][maxn];
 };

 //矩阵间的乘法
 Matrix matrix_mul(Matrix A, Matrix B){
     Matrix ans;
     for (int i = ; i < maxn; i++){
         for (int j = ; j < maxn; j++){
             ans.v[i][j] = ;
             for (int k = ; k < maxn; k++){
                 ans.v[i][j] += (A.v[i][k] * B.v[k][j]) % m;
             }
             ans.v[i][j] %= m;
         }
     }
     return ans;
 }

 Matrix matrix_pow(Matrix C, LL n){
     Matrix ans = { , , ,  };
     while (n){
         if (n & ){
             ans = matrix_mul(ans, C);
         }
         C = matrix_mul(C, C);
         n >>= ;
     }
     return ans;
 }

 int main(){
     ios::sync_with_stdio(false);

     LL n;
     cin >> n;
     Matrix e = { , , ,  };
     Matrix ee = { , , ,  };
     Matrix ans = matrix_pow(ee, n - );
     ans = matrix_mul(e, ans);
     cout << ans.v[][] << endl;
     //system("pause");
     return ;
 }