明白了
```cpp
if(dis[v = p->v] - dis[u] + p->w <= k && dis[v = p->v] - dis[u] + p->w >= 0)
```
这个值还要$>=0$，不然后面减出来会$>=50$
by Gypsophila @ 2018-05-07 16:30:47
orz lcj
by hacker047 @ 2018-08-27 18:07:49