38 lines
954 B
Python
38 lines
954 B
Python
from collections import defaultdict
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class Solution:
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def canFinish(self, numCourses: int, prerequisites: List[List[int]]) -> bool:
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graph = defaultdict(list)
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for course, pre in prerequisites:
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graph[course].append(pre)
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cycles = set()
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visited = set()
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def dfs(course):
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if course in cycles:
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return False
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if course in visited:
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return True
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visited.add(course)
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cycles.add(course)
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for dep in graph[course]:
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if not dfs(dep):
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return False
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cycles.remove(course)
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return True
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for course in range(numCourses):
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cycles = set()
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if not dfs(course):
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return False
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return True
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