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hello-algo/codes/python/chapter_graph/graph_adjacency_list.py

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"""
File: graph_adjacency_list.py
Created Time: 2023-02-23
Author: Krahets (krahets@163.com)
"""
import sys, os.path as osp
sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
from include import *
""" 基于邻接表实现的无向图类 """
class GraphAdjList:
# 邻接表key: 顶点value该顶点的所有邻接顶点
adj_list = {}
""" 构造方法 """
def __init__(self, edges: List[List[Vertex]]) -> None:
self.adj_list = {}
# 添加所有顶点和边
for edge in edges:
self.add_vertex(edge[0])
self.add_vertex(edge[1])
self.add_edge(edge[0], edge[1])
""" 获取顶点数量 """
def size(self) -> int:
return len(self.adj_list)
""" 添加边 """
def add_edge(self, vet1: Vertex, vet2: Vertex) -> None:
if vet1 not in self.adj_list or vet2 not in self.adj_list or vet1 == vet2:
raise ValueError
# 添加边 vet1 - vet2
self.adj_list[vet1].append(vet2)
self.adj_list[vet2].append(vet1)
""" 删除边 """
def remove_edge(self, vet1: Vertex, vet2: Vertex) -> None:
if vet1 not in self.adj_list or vet2 not in self.adj_list or vet1 == vet2:
raise ValueError
# 删除边 vet1 - vet2
self.adj_list[vet1].remove(vet2)
self.adj_list[vet2].remove(vet1)
""" 添加顶点 """
def add_vertex(self, vet: Vertex) -> None:
if vet in self.adj_list:
return
# 在邻接表中添加一个新链表
self.adj_list[vet] = []
""" 删除顶点 """
def remove_vertex(self, vet: Vertex) -> None:
if vet not in self.adj_list:
raise ValueError
# 在邻接表中删除顶点 vet 对应的链表
self.adj_list.pop(vet)
# 遍历其它顶点的链表,删除所有包含 vet 的边
for vertex in self.adj_list:
if vet in self.adj_list[vertex]:
self.adj_list[vertex].remove(vet)
""" 打印邻接表 """
def print(self) -> None:
print("邻接表 =")
for vertex in self.adj_list:
tmp = [v.val for v in self.adj_list[vertex]]
print(f"{vertex.val}: {tmp},")
""" Driver Code """
if __name__ == "__main__":
""" 初始化无向图 """
v = vals_to_vets([1, 3, 2, 5, 4])
edges = [[v[0], v[1]], [v[0], v[3]], [v[1], v[2]],
[v[2], v[3]], [v[2], v[4]], [v[3], v[4]]]
graph = GraphAdjList(edges)
print("\n初始化后,图为")
graph.print()
""" 添加边 """
# 顶点 1, 2 即 v[0], v[2]
graph.add_edge(v[0], v[2])
print("\n添加边 1-2 后,图为")
graph.print()
""" 删除边 """
# 顶点 1, 3 即 v[0], v[1]
graph.remove_edge(v[0], v[1])
print("\n删除边 1-3 后,图为")
graph.print()
""" 添加顶点 """
v5 = Vertex(6)
graph.add_vertex(v5)
print("\n添加顶点 6 后,图为")
graph.print()
""" 删除顶点 """
# 顶点 3 即 v[1]
graph.remove_vertex(v[1])
print("\n删除顶点 3 后,图为")
graph.print()