Aggregate spending by path
A school tracks spending against slash-separated category paths. Each row is "path,amount" where path looks like "supplies/art/paint" and amount is a positive integer. Every amount counts toward its own path AND every ancestor prefix, so "it/laptops,300" adds 300 to both "it" and "it/laptops". Return a dictionary mapping every path that received money (directly or via a descendant) to its total. Example: ["it/laptops,300", "it/software,100", "sports,50"] gives {"it": 400, "it/laptops": 300, "it/software": 100, "sports": 50}.
rollup_totals(rows: list[str]) → dict[str,int][["it/laptops,300","it/software,100","sports,50"]]out{"it":400,"sports":50,"it/laptops":300,"it/software":100}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.
[["it/laptops,300","it/software,100","sports,50"]]{"it":400,"sports":50,"it/laptops":300,"it/software":100}not run yetsample