Range sum in BST
Given a binary search tree as a level-order array `arr` (null for missing) and an inclusive range `[lo, hi]`, return the sum of all node values v with `lo <= v <= hi`. The tree is a valid BST. Prune branches that cannot contain in-range values. `0 <= node count <= 100000`, `lo <= hi`.
Implement
range_sum_bst(arr: list[int], lo: int, hi: int) → intExamples
in
[[10,5,15,3,7,null,18],7,15]out32What a strong answer looks like
State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.
0:00 of about 20 min
solution.py
InputExpectedGot
[[10,5,15,3,7,null,18],7,15]32not run yetsample