Course Schedule
There are numCourses courses labeled 0 to numCourses−1, and a list of prerequisite pairs where [a, b] means you must finish course b before taking course a. Return true if it is possible to finish every course, false otherwise. Up to 2000 courses and 5000 prerequisite pairs.
Examples
- Input:
- numCourses = 2, prerequisites = [[1,0]]
- Output:
- true
Take course 0 first, then course 1.
- Input:
- numCourses = 2, prerequisites = [[1,0],[0,1]]
- Output:
- false
Course 1 needs 0 first, and course 0 needs 1 first — a circular requirement no order can satisfy.
- Input:
- numCourses = 3, prerequisites = [[1,0],[2,1]]
- Output:
- true
A simple chain: 0, then 1, then 2.
Hints
One at a time — struggle first, peek second.
Your thinking space — verify on LeetCode, then mark it.