Course Schedule

Problem

Given num_courses and prerequisite pairs [a, b] meaning course b must be taken before course a, return True if all courses can be finished.

Build the directed graph and indegrees, then repeatedly remove zero-indegree nodes; if fewer than num_courses nodes are removed, a cycle exists. An empty prerequisite list is always feasible.

Hint

If Kahn's algorithm cannot remove every node, the remaining nodes form at least one cycle.

Test cases

case 1

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

expected: true

case 2

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

expected: false

case 3

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

expected: true

case 4

in: [3,[]]

expected: true

case 5

in: [1,[]]

expected: true

Starter codePython

def can_finish_courses(num_courses, prerequisites):
    # Your code here
    pass

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