Function Inclusive / Exclusive Time

Given a list of `(function_id, start|end, timestamp)` log lines, compute the inclusive and exclusive elapsed time for a target function. LeetCode 636 variant — stack-based bookkeeping where each `start` pushes a context and each `end` pops while attributing elapsed time to the *current top* of the stack. Requirements def function_times(logs: list[str], target: str) -> tuple[int, int]: # logs: ["AB:start:0", "CD:start:3", "EF:start:5", "EF:end:6", # "CD:end:8", "AB:end:9"] # returns (inclusive, exclusive) Definitions: Inclusive time of target: the wall-clock span between its outermost start and the matching end. Exclusive time of target: inclusive time minus the time charged to any function that started while target was on the stack (its direct children's inclusive time at the first-generation level). The canonical solution maintains a stack of (function_id, last_resume_ts, accumulated_exclusive). On a start event, charge (now - prev_top.last_resume_ts) to whatever is currently on top, then push the new function. On end, pop and accumulate. The reported variant also asks for only-first-generation children to be excluded — i.e. nested grandchildren are still counted toward target's exclusive time. Clarify with the interviewer; the standard LC 636 definition excludes all nested time. Examples logs = ["AB:start:0", "CD:start:3", "EF:start:5", "EF:end:6", "CD:end:8", "AB:end:9"] target = "AB" inclusive(AB) = 9 - 0 + 1 = 10 (typical LC semantics; check inclusive/exclusive of end ts) exclusive(AB) = 10 - inclusive(CD) = 10 - 6 = 4 Verify with the interviewer whether timestamps are point-in-time or unit-duration ticks — both conventions appear. Notes The trap is forgetting to charge time to the previous top before pushing — many candidates only update on end, which double-counts. LC 636 uses unit-tick semantics (end - start + 1); the LinkedIn variant uses point-in-time (end - start). Confirm before coding. The first-generation exclusion subtlety is what differentiates this from straight LC 636 — be ready to redefine. Preparation Memorize the LC 636 stack pattern; this question is the same skeleton with renamed semantics. Practice asking the inclusive/exclusive boundary question first — it saves rework. Sketch a recursion-tree diagram for the example before coding; the visual makes the per-frame accounting obvious.