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

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"""
File: graph_dfs.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 *
from graph_adjacency_list import GraphAdjList
""" 深度优先遍历 DFS 辅助函数 """
def dfs(graph: GraphAdjList, visited: Set[Vertex], res: List[Vertex], vet: Vertex):
res.append(vet) # 记录访问顶点
visited.add(vet) # 标记该顶点已被访问
# 遍历该顶点的所有邻接顶点
for adjVet in graph.adj_list[vet]:
if adjVet in visited:
continue # 跳过已被访问过的顶点
# 递归访问邻接顶点
dfs(graph, visited, res, adjVet)
""" 深度优先遍历 DFS """
# 使用邻接表来表示图,以便获取指定顶点的所有邻接顶点
def graph_dfs(graph: GraphAdjList, start_vet: Vertex) -> List[Vertex]:
# 顶点遍历序列
res = []
# 哈希表,用于记录已被访问过的顶点
visited = set()
dfs(graph, visited, res, start_vet)
return res
""" Driver Code """
if __name__ == "__main__":
# 初始化无向图
v = vals_to_vets([0, 1, 2, 3, 4, 5, 6])
edges = [[v[0], v[1]], [v[0], v[3]], [v[1], v[2]],
[v[2], v[5]], [v[4], v[5]], [v[5], v[6]]]
graph = GraphAdjList(edges)
print("\n初始化后,图为")
graph.print()
# 深度优先遍历 BFS
res = graph_dfs(graph, v[0])
print("\n深度优先遍历DFS顶点序列为")
print(vets_to_vals(res))