@[让风忽悠你](/user/224926)
```cpp
int query(int L,int R,int k,int l,int r){
if(L<=l && r<=R) return w[k];
int mid=(l+r)>>1,res=0;
push_down(k,r-l+1);
if(L<=mid) res+=query(L,R,lson,l,mid);
if(R>mid) res+=query(L,R,rson,mid+1,r);
push_up(k); return res;
}
```
记得 `return` 东西（
by zhiyangfan @ 2022-01-20 16:40:39
[借楼求助](https://www.luogu.com.cn/discuss/399901)
by yzh_Error404 @ 2022-01-20 16:41:28
[~~借楼求换根dp~~](https://www.luogu.com.cn/discuss/399877)
by Leonid @ 2022-01-20 16:43:47
@[zhiyangfan](/user/137603) 谢谢大佬（话说您好像帮了我好多次）
by 让风忽悠你 @ 2022-01-20 16:45:14
@[让风忽悠你](/user/224926) 树剖的板子题之前晚自习快水的差不多了，所以看见树剖都能帮忙看一下（
by zhiyangfan @ 2022-01-20 16:49:22