Course Schedule & Cycle Detection (Topological Sort)

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] = [a, b]` indicates that you must take course `b` first if you want to take course `a`. Return `true` if you can finish all courses, or `false` if a cycle exists making it impossible. ### Constraints - `1 <= numCourses <= 2000` - `0 <= prerequisites.length <= 5000` - `prerequisites[i].length == 2` - All pairs `[a, b]` are unique. ### Input Format First line contains integer `numCourses`. Second line contains integer `numPrerequisites`. Next lines contain two space-separated integers `a b` representing each prerequisite pair. ### Output Format Print `true` if all courses can be finished, otherwise `false`.