Topological Sort Problem

Given a directed acyclic graph representing the prerequisite relationship of courses, find an order to complete all courses as required. If course A is a prerequisite of course B, A must be earlier in the sequence than B. Implement a function findOrder(numCourses, prerequisites) to return a valid course order. Input numCourses is an integer indicating the number of courses, prerequisites is a list where each element is a list of two integers representing a prerequisite relationship where the first integer is the course and the second is the prerequisite. Example Input: numCourses = 2, prerequisites = [[1,0]] Output: [0,1] Input: numCourses = 4, prerequisites = [[1,0],[2,0],[3,1],[3,2]] Output: [0,1,2,3] or [0,2,1,3] Constraints Number of courses is in the range [1, 2000] Number of prerequisites will not exceed numCourses * (numCourses - 1) Note: If there is no possible course order, return an empty list. Example Input 2 [[1,0]]