1466. 重新规划路线

class Solution(object):
    def minReorder(self, n, connections):
        """
        :type n: int
        :type connections: List[List[int]]
        :rtype: int
        """
        # 记录所有点的出、入度:0表示入度，1表示出度
        edge = [[] for _ in range(n)]
        # 遍历参数中的边，每条边的两个端点都要记录相应的出、入度
        for start, end in connections:
            edge[start].append((end, 1))
            edge[end].append((start, 0))
        print(edge)
        # 设置每个点的访问标记，避免重复访问；对于本题，0点初始化是已访问的
        visit = [False] * n
        visit[0] = True
        # 返回值
        ans = 0
        # 开始BFS
        already = [0]
        while already:
            cur = already.pop(0)
            print(visit, edge[cur])
            for index, degree in edge[cur]:
                if not visit[index]:
                    visit[index] = True
                    ans += degree
                    already.append(index)
        return ans


if __name__ == '__main__':
    s = Solution()
    print(s.minReorder(5, [[4, 3], [2, 3], [1, 2], [1, 0]]))