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Course Schedule II

Question​

None

Example 1
Input: numCourses = 2, prerequisites = [[1,0]] 
Output: [0,1]

Solution​

all//Course Schedule II.py


class Solution:
    def findOrder(self, numCourses, prerequisites):
        in_degree = [[] for _ in range(numCourses)]
        out_degree = [0] * numCourses
        for x, y in prerequisites:
            in_degree[y].append(x)
            out_degree[x] += 1
        queue = []
        for i in range(numCourses):
            if out_degree[i] == 0:
                queue.append(i)
        res = []
        while queue:
            course = queue.pop(0)
            res.append(course)
            for x in in_degree[course]:
                out_degree[x] -= 1
                if out_degree[x] == 0:
                    queue.append(x)
        if len(res) != numCourses:
            return []
        return res