Course Schedule
Difficulty: Medium
Category: DSA
Topics: Depth-First Search, Breadth-First Search, Graph, Topological Sort
Asked at: Amazon, Intuit, Facebook, Karat, Microsoft, ByteDance, Bloomberg, Google
There are a total of `numCourses` courses you have to take, labeled from `0` to `numCourses - 1`. You are given an array `prerequisites` where `prerequisites[i] = [ai, bi]` indicates that you **must** take course `bi` first if you want to take course `ai`.
- For example, the pair `[0, 1]`, indicates that to take course `0` you have to first take course `1`.
Return `true` if you can finish all courses. Otherwise, return `false`.
**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 have finished course 0. So it is possible.
```
**Example 2:**
**Input:** numCourses = 2, prerequisites = [[1,0],[0,1]]
**Output:** false
**Explanation:** There are a total of 2 courses to take.
To take course 1 you should have finished course 0, and to take course 0 you should also have finished course 1. So it is impossible.
```
**Constraints:**
- `1 <= numCourses <= 2000`
- `0 <= prerequisites.length <= 5000`
- `prerequisites[i].length == 2`
- `0 <= ai, bi < numCourses`
- All the pairs prerequisites[i] are **unique**.