leetcode.com 210. Course Schedule II

문제 링크: https://leetcode.com/problems/course-schedule-ii

Author: skysign

leetcode.com 210. Course Schedule II v2/main.py

@@ -0,0 +1,34 @@
+from typing import List
+from collections import deque
+
+class Solution:
+    def findOrder(self, numCourses: int, prerequisites: List[List[int]]) -> List[int]:
+        incoming_edge = [0 for _ in range(numCourses)]
+        edge = [[] for _ in range(numCourses)]
+        answer = []
+        queue = deque()
+
+        for to, fr in prerequisites:
+            edge[fr].append(to)
+            incoming_edge[to] += 1
+
+        for i in range(numCourses):
+            if incoming_edge[i] == 0:
+                queue.append(i)
+
+        while queue:
+            fr = queue.popleft()
+            answer.append(fr)
+
+            for to in edge[fr]:
+                incoming_edge[to] -= 1
+                if incoming_edge[to] == 0:
+                    queue.append(to)
+
+        for i in range(numCourses):
+            if incoming_edge[i] != 0:
+                # cycle이 있어서, course를 수강하는게 불가능한 경우
+                return []
+
+        return answer
+

leetcode.com 210. Course Schedule II v2/test_main.py

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+from unittest import TestCase
+from main import Solution
+
+class TestSolution(TestCase):
+    def test_find_order(self):
+        sln = Solution()
+        self.assertEqual([0,1], sln.findOrder(2, [[1,0]]))