`root` 开小了。建议改成这样。
```cpp
int dfs(int cot)
{
int now, root = 0, lef, rig;
cin >> now;
if (now) {
update(root, 1, n, now);
return root;
}
root = lef = dfs(ls), rig = dfs(rs), u = v = 0;
root = merge(root, rig, 1, n);
ans += min(u, v);
return root;
}
```
by Pholsautte @ 2023-01-13 13:37:34
@[Pholsautte](/user/597395) 好的 , 我试试
by Saka_Noa @ 2023-01-13 13:43:58
@[Pholsautte](/user/597395) 谢谢 , 过了
by Saka_Noa @ 2023-01-13 13:45:20