in swift, given there's a list of tasks with their effort (in days) [("painting", 5), ("drywall", 2) ...] and a list of dependencies that show pairs of task, task1 relies on task2 so [ ("painting", "drywall"), ("drywall", "hvac"), ("drywall", "plumbing") ] means painting relies on drywall, and drywall relies on hvac, plumbing etc. give the earliest amount of time for a given task.