这不没区别吗（
BIT是可以 $O(n)$ 建树，但你这样是 $O(nlogn)$ 的
by Stinger @ 2021-04-16 13:27:42
@[zhangqs](/user/361308) 求教怎么O（n）建树
by Engiassca @ 2021-04-16 13:38:18
@[Engiassca](/user/353113) 差分一下就好了，像线段树懒标记一样，单点加，然后顺序遍历一遍加上标记
by RedreamMer @ 2021-04-16 13:52:07
@[RedreamMer](/user/184549) 没听懂...请问可以放下代码吗
by Engiassca @ 2021-04-16 13:59:37
```cpp
for (int i = 1; i <= a; i++) {
s[i] = read();
p[s[i]]++;
}
for (int i = 1; i <= max_val; i++) {
p[i + (i & -i)] += p[i];
}
```
by RedreamMer @ 2021-04-16 15:34:44