[luoguP1962] 斐波那契数列（矩阵快速幂）

传送门

解析详见julao博客连接 http://worldframe.top/2017/05/10/清单-数学方法-——-矩阵/

——代码

 #include <cstdio>
 #include <cstring>
 #define LL long long

 LL n;
 const int p = 1e9 + ;

 struct Matrix
 {
     LL a[][];
     Matrix()
     {
         memset(a, , sizeof(a));
     }
 };

 inline Matrix operator * (const Matrix x, const Matrix y)
 {
     Matrix ans;
     int i, j, k;
     for(i = ; i < ; i++)
         for(j = ; j < ; j++)
             for(k = ; k < ; k++)
                 ans.a[i][j] = (ans.a[i][j] + x.a[i][k] * y.a[k][j]) % p;
     return ans;
 }

 inline int pow(LL x)
 {
     Matrix ans, trs;
     ans.a[][] = ans.a[][] = ;
     trs.a[][] = trs.a[][] = trs.a[][] = ;
     while(x)
     {
         if(x & ) ans = ans * trs;
         trs = trs * trs;
         x >>= ;
     }
     return ans.a[][];
 }

 int main()
 {
     scanf("%lld", &n);
     printf("%d\n", pow(n - ));
     return ;
 }