LeetCode #207 - Course Schedule

There are 'n' courses you have to take, labeled from 0 to n - 1. Some courses may have prerequisites, represented as a pair of course pairs (a, b) that means you must take course b before course a. Given an array of prerequisite pairs, return true if you can finish all courses, or false if you cannot.

Example 1:

Input: numCourses = 2, prerequisites = [[1,0]]
Output: true
Explanation: There are a total of 2 courses to take. To take course 1, you should already have taken course 0. So it is possible.

Example 2:

Input: numCourses = 2, prerequisites = [[1,0],[0,1]]
Output: false
Explanation: There is a cycle in the prerequisites.

Constraints:

• 1 <= numCourses <= 2000


• 0 <= prerequisites.length <= 5000


• prerequisites[i].length == 2


• All prerequisite pairs are unique.