Course Schedule

Statement

You are given an integer, num_courses, representing the total number of courses you need to complete, labeled from 0 to num_courses - 1.

You are also given a prerequisites array, where prerequisites[i] = [a[i], b[i]] indicates that you must take course b[i] first if you want to take the course a[i]. For example, the pair $[1, 0]$ indicates that to take course $1$, you have to first take course $0$.

Return TRUE if all of the courses can be finished. Otherwise, return FALSE.

Constraints:

• $1 \leq$ num_courses $\leq 1500$
• $0 \leq$ prerequisites.length $\leq 1000$
• prerequisites[i].length $= 2$
• $0 \leq$ a[i], b[i] $<$ num_courses
• All the pairs prerequisites[i] are unique.

Examples