Course Schedule Order

Problem

Given num_courses courses labeled 0 to num_courses-1 and prerequisite pairs [a, b] meaning b must be taken before a, return a valid course order.

Always take the smallest available course first (lexicographically smallest order). Return an empty list when the prerequisites contain a cycle.

Hint

Build edges from prerequisite to course, then run Kahn with a min-heap.

case 1

in: [4,[[1,0],[2,0],[3,1],[3,2]]]

expected: [0,1,2,3]

case 2

in: [2,[[1,0]]]

expected: [0,1]

case 3

in: [2,[[1,0],[0,1]]]

expected: []

case 4

in: [3,[[0,1],[1,2]]]

expected: [2,1,0]

case 5

in: [3,[]]

expected: [0,1,2]

Starter codePython

import heapq
def course_schedule_order(num_courses, prerequisites):
    # Your code here
    pass

5 test cases · run your code against them in the editor