Course Schedule

Medium

There are n courses labeled 0..n-1. edges[i] = [a, b] means you must take course b before course a. Return true if you can finish all courses.

Example 1

Input:  n = 2, edges = [[1,0]]
Output: true

Example 2

Input:  n = 2, edges = [[1,0],[0,1]]
Output: false

Constraints

• 1 <= n <= 2000
• 0 <= edges.length <= 5000