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Question
Maintain a Fenwick (binary indexed) tree over an initial integer array arr. Process operations: ["update", i, v] SETS arr[i] = v (an assignment, not an increment), and ["query", l, r] returns the sum of the inclusive range [l, r]. Indices are 0-based. Return the list of answers to the "query" operations, in order.
Implement
fenwick_point_update_range_sum(arr: list[int], ops: list[list]) → list[int]Examples
in
[[1,2,3,4,5],[["query",0,4],["update",2,10],["query",0,4],["query",2,2]]]out[15,22,10]What 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.
Learn the concepts
Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.
Run or narrate your approach, then ask the coach.