拓扑排序模板

0X00 模板

直接拿 207 的题解吧

from collections import deque
class Solution:
    def canFinish(self, numCourses: int,prerequisites: List[List[int]]) -> bool:
        indegrees = [0 for _ in range(numCourses)]
        adjacency = [[]for _ in range(numCourses)]

        # 构造入度表和拓扑
        for cur, pre in prerequisites:
            indegrees[cur] += 1
            adjacency[pre].append(cur)
        
        # 构造 0 入度队列
        queue = deque()
        for i in range(numCourses):
            if indegrees[i] == 0: queue.append(i)
        
        # BFS 拓扑排序
        while queue:
            pre = queue.popleft()
            numCourses -= 1
            # pre 后面的都减一
            for  follow in adjacency[pre]:
                indegrees[follow] -= 1
                if not indegrees[follow]: queue.append(follow)
        
        return not numCourses

0X01 注意事项

暂无

0X02 相关题目

• 207. Course Schedule

• 210. Course Schedule II

• 802. Find Eventual Safe States