xdm，找出来了，这段代码：
```cpp
if (0 < tx && tx <= m && 0 < ty && ty <= n && !vis[tx][ty][tmp.d]) {
vis[tx][ty][tmp.d] = 1;
node t;
t.x = tx;
t.y = ty;
t.dis = tmp.dis + 1;
t.d = i;
q.push(t);
```
应该改成
```cpp
if (0 < tx && tx <= m && 0 < ty && ty <= n && !vis[tx][ty][i]) {
vis[tx][ty][i] = 1;
node t;
t.x = tx;
t.y = ty;
t.dis = tmp.dis + 1;
t.d = i;
q.push(t);
}
```
再此警示后人
by farfar @ 2022-05-20 10:09:02