self.graph = defaultdict(list) self.graph[u].append(v)
时间: 2024-06-06 21:10:38 浏览: 147
These lines of code are creating a graph data structure using a defaultdict from the Python collections module.
The graph is represented as a dictionary where each key is a vertex (node) in the graph and the value is a list of the vertices that the key vertex is connected to by edges.
The first line initializes the graph as a defaultdict with a default value of an empty list. This means that when a key is accessed that does not exist in the dictionary, it will automatically create an empty list as the value for that key.
The second line adds a new edge to the graph by appending the vertex v to the list of vertices that are connected to the vertex u.
Overall, these lines of code are used to build a graph by adding edges between vertices as needed.
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