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"""
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File: graph_adjacency_list.py
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Created Time: 2023-02-23
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Author: krahets (krahets@163.com)
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"""
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import sys
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from pathlib import Path
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sys.path.append(str(Path(__file__).parent.parent))
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from modules import Vertex, vals_to_vets
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class GraphAdjList:
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"""基于邻接表实现的无向图类"""
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def __init__(self, edges: list[list[Vertex]]):
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"""构造方法"""
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# 邻接表，key：顶点，value：该顶点的所有邻接顶点
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self.adj_list = dict[Vertex, list[Vertex]]()
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# 添加所有顶点和边
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for edge in edges:
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self.add_vertex(edge[0])
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self.add_vertex(edge[1])
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self.add_edge(edge[0], edge[1])
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def size(self) -> int:
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"""获取顶点数量"""
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return len(self.adj_list)
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def add_edge(self, vet1: Vertex, vet2: Vertex):
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"""添加边"""
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if vet1 not in self.adj_list or vet2 not in self.adj_list or vet1 == vet2:
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raise ValueError()
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# 添加边 vet1 - vet2
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self.adj_list[vet1].append(vet2)
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self.adj_list[vet2].append(vet1)
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def remove_edge(self, vet1: Vertex, vet2: Vertex):
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"""删除边"""
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if vet1 not in self.adj_list or vet2 not in self.adj_list or vet1 == vet2:
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raise ValueError()
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# 删除边 vet1 - vet2
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self.adj_list[vet1].remove(vet2)
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self.adj_list[vet2].remove(vet1)
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def add_vertex(self, vet: Vertex):
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"""添加顶点"""
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if vet in self.adj_list:
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return
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# 在邻接表中添加一个新链表
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self.adj_list[vet] = []
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def remove_vertex(self, vet: Vertex):
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"""删除顶点"""
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if vet not in self.adj_list:
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raise ValueError()
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# 在邻接表中删除顶点 vet 对应的链表
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self.adj_list.pop(vet)
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# 遍历其他顶点的链表，删除所有包含 vet 的边
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for vertex in self.adj_list:
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if vet in self.adj_list[vertex]:
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self.adj_list[vertex].remove(vet)
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def print(self):
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"""打印邻接表"""
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print("邻接表 =")
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for vertex in self.adj_list:
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tmp = [v.val for v in self.adj_list[vertex]]
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print(f"{vertex.val}: {tmp},")
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"""Driver Code"""
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if __name__ == "__main__":
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# 初始化无向图
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v = vals_to_vets([1, 3, 2, 5, 4])
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edges = [
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[v[0], v[1]],
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[v[0], v[3]],
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[v[1], v[2]],
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[v[2], v[3]],
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[v[2], v[4]],
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[v[3], v[4]],
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]
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graph = GraphAdjList(edges)
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print("\n初始化后，图为")
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graph.print()
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# 添加边
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# 顶点 1, 2 即 v[0], v[2]
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graph.add_edge(v[0], v[2])
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print("\n添加边 1-2 后，图为")
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graph.print()
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# 删除边
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# 顶点 1, 3 即 v[0], v[1]
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graph.remove_edge(v[0], v[1])
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print("\n删除边 1-3 后，图为")
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graph.print()
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# 添加顶点
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v5 = Vertex(6)
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graph.add_vertex(v5)
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print("\n添加顶点 6 后，图为")
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graph.print()
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# 删除顶点
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# 顶点 3 即 v[1]
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graph.remove_vertex(v[1])
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print("\n删除顶点 3 后，图为")
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graph.print()
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