@[顾瑀丶](/space/show?uid=153898) %%%tql
by zh_dou @ 2019-06-07 18:29:29
```cpp
martix operator * (const martix & a,const martix & b)
{
martix res;
memset(res.f,0,sizeof res.f);
for(int k = 1;k <= 3;k ++) for(int i = 1;i <= 3;i ++) for(int j = 1;j <= 3;j ++)
res.f[i][j] = (res.f[i][j] + res.f[i][k] * res.f[k][j] % m) % m;
return res;
}
```
你初始化成0之后怎么加怎么乘都是0吧
@[顾瑀丶](/space/show?uid=153898)
by 我惠美如画 @ 2019-06-07 18:35:40
```cpp
martix operator * (const martix & a,const martix & b)
{
martix res;
memset(res.f,0,sizeof res.f);
for(int k = 1;k <= 3;k ++) for(int i = 1;i <= 3;i ++) for(int j = 1;j <= 3;j ++)
res.f[i][j] = (res.f[i][j] + res.a[i][k] * res.b[k][j] % m) % m;
return res;
}
```
by zh_dou @ 2019-06-07 18:36:33
$ res.a[i][k] * res.b[k][j]$
不是
$ res.f[i][k] * res.f[k][j]$
by zh_dou @ 2019-06-07 18:37:41
orzorz
by ΦωΦ @ 2019-06-07 18:42:25
@[顾瑀丶](/space/show?uid=153898) %%%tql
by __wfx @ 2019-06-07 18:57:49
@[我惠美如画](/space/show?uid=146702) 矩阵快速幂就是这样写的
~~~cpp
martix operator * (const martix & a , const martix & b)
{
martix res;
memset(res.f,0,sizeof res.f );
for(int k = 1;k <= n;k ++)
for(int i = 1;i <= n;i ++)
for(int j = 1;j <= n;j ++)
res.f[i][j] = (res.f[i][j] + a.f[i][k] * b.f[k][j] % mod) % mod;
return res;
}
~~~
by Treaker @ 2019-06-07 19:02:13
@[顾瑀丶](/space/show?uid=153898) 矩阵快速幂中$res$应初始为单位元矩阵
就是
$$
\left\{
\begin{matrix}
1 & 2 & 3 \\
4 & 5 & 6 \\
7 & 8 & 9
\end{matrix}
\right\}
$$
by __wfx @ 2019-06-07 19:04:26
@[顾瑀丶](/space/show?uid=153898)
你没发现这个和你代码里的不一样吗
by 我惠美如画 @ 2019-06-07 19:04:54
@[我惠美如画](/space/show?uid=146702) 发现了 ， 但还是不对
by Treaker @ 2019-06-07 20:13:29