DIY: Course Schedule

Problem statement

You will be given an integer num_courses representing the number of courses. The courses are labeled from 0 to num_courses - 1. You will also be given an array prerequisites where prerequisites[i] = [ai, bi] indicates that you must take course bi first if you want to take the course ai. For example, the pair [1, 0], indicates that to take course 1 you have to first take course 0.

You will have to return true if all of the courses can be finished, otherwise false.