@[不知不觉lb](/space/show?uid=22250) @[star_city](/space/show?uid=47421) @[shzr](/space/show?uid=34204) @[Itst](/space/show?uid=96296) 求助qaq
by flashess @ 2019-03-10 22:38:02
@[flashess](/space/show?uid=89012)
好像是之前用高斯消元的方法求行列式的时候，把
```cpp
for(int i = 2 ; i <= N ; ++i){
for(int j = i ; j <= N ; ++j)
if(mat[j][i]){
swap(mat[i] , mat[j]);
if(i != j)
ans = MOD - ans;
break;
}
int t = poww(mat[i][i] , MOD - 2);
for(int j = i + 1 ; j <= N ; ++j)
if(mat[j][i])
for(int k = N ; k >= i ; --k)
mat[j][k] = (mat[j][k] - mat[i][k] * t % MOD * mat[j][i] % MOD + MOD) % MOD;
}
```
写成了
```cpp
for(int i = 2 ; i <= N ; ++i){
int t = poww(mat[i][i] , MOD - 2);
for(int j = i + 1 ; j <= N ; ++j)
if(mat[j][i])
for(int k = N ; k >= i ; --k)
mat[j][k] = (mat[j][k] - mat[i][k] * t % MOD * mat[j][i] % MOD + MOD) % MOD;
}
```
by Itst @ 2019-03-10 22:40:18
@[Itst](/space/show?uid=96296) 完了，忘了行列式性质了qaq
by flashess @ 2019-03-10 22:43:29
@[Itst](/space/show?uid=96296) 膜拜[Itst](/space/show?uid=96296)巨佬%%%
by flashess @ 2019-03-10 22:44:08
@[flashess](/space/show?uid=89012) 我可能是被重边坑了？
by star_city @ 2019-03-10 22:55:41
@[star_city](/space/show?uid=47421) 应该是没有重边的呀，蒟蒻刚assert了下
by flashess @ 2019-03-10 23:12:44
@[flashess](/space/show?uid=89012) 那就是高斯消元交换的时候写挂了吧qwq
by star_city @ 2019-03-10 23:51:46
@[flashess](/space/show?uid=89012) 另外您别装弱啊~~我lct都是看的您blog学的qwq~~
by star_city @ 2019-03-10 23:52:28
我得90的那次是交换行时答案没取反qwq
@[flashess](/space/show?uid=89012)
by shzr @ 2019-03-11 13:42:34
@[shzr](/space/show?uid=34204) @[star_city](/space/show?uid=47421) +1，实在是随手一码就忘了qwq
by flashess @ 2019-03-11 13:51:35