Zkw线段树 Free May 2026

Prefix sum [0, r] :

On a sum tree, find smallest p such that sum[0..p] >= k . zkw线段树

int lower_bound(int k) int pos = 1; while (pos < N) if (tree[pos<<1] < k) k -= tree[pos<<1]; pos = pos<<1 else pos = pos<<1; return pos - N; Prefix sum [0, r] : On a sum