Code Room
CodingMediumcod-g504
Subject Topological sortLevel Mid–Senior~30 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

A build system runs n tasks (0..n-1), each with a positive duration durations[i]. Dependencies are pairs [a, b] meaning task b can only start after task a finishes; independent tasks run fully in parallel. Return the makespan — the minimum total time to finish all tasks given unlimited parallelism — which equals the longest dependency chain weighted by durations (the critical path). If the dependencies form a cycle, return -1.

Implement
critical_path(durations: list[int], deps: list[list[int]]) → int
Examples
in[[3,2,5,1],[[0,1],[1,3],[0,2],[2,3]]]out9
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.

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.