leetcode.com 207. Course Schedule

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

Author: skysign

leetcode.com 207. Course Schedule v2/main.py

@@ -0,0 +1,42 @@
+from typing import List
+from collections import deque
+
+class Solution:
+    def canFinish(self, numCourses: int, prerequisites: List[List[int]]) -> bool:
+        class Vertex:
+            def __init__(self, v):
+                self.v = v
+                self.incoming = []
+                self.outgoing = []
+
+        vertexes = {}
+
+        for fr, to in prerequisites:
+            if fr not in vertexes.keys():
+                vertexes[fr] = Vertex(fr)
+
+            if to not in vertexes.keys():
+                vertexes[to] = Vertex(to)
+
+            vertexes[fr].outgoing.append(to)
+            vertexes[to].incoming.append(fr)
+
+        queue = deque()
+
+        for vertex in list(vertexes.values()):
+            if len(vertex.incoming) == 0:
+                queue.append(vertex)
+
+        while queue:
+            vertex = queue.popleft()
+            fr = vertex.v
+
+            for to in vertex.outgoing:
+                vertexes[to].incoming.remove(fr)
+
+                if len(vertexes[to].incoming) == 0:
+                    queue.append(vertexes[to])
+
+            del vertexes[fr]
+
+        return len(vertexes.values()) == 0

leetcode.com 207. Course Schedule v2/test_main.py

@@ -0,0 +1,8 @@
+from unittest import TestCase
+from main import Solution
+
+
+class TestSolution(TestCase):
+    def test1_can_finish(self):
+        sln = Solution()
+        self.assertEqual(True, sln.canFinish(numCourses = 2, prerequisites = [[1,0]]))