#624 · #2050 · Parallel Courses III(并行课程 III)

You are given n courses, relations[i] = [a, b] meaning a must be taken before b, and time[i] for the duration of course i+1. Courses with satisfied prerequisites run in parallel. Return the minimum time to complete all courses. Constraints: 1 <= n <= 5 * 10^4, 0 <= relations.length <= min(n*(n-1)/2, 5*10^4), 1 <= time[i] <= 10^4.