hello-algo/codes/ruby/chapter_graph/graph_bfs.rb
2024-04-26 17:30:55 +08:00

61 lines
1.5 KiB
Ruby
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

=begin
File: graph_bfs.rb
Created Time: 2024-04-25
Author: Xuan Khoa Tu Nguyen (ngxktuzkai2000@gmail.com)
=end
require 'set'
require_relative './graph_adjacency_list'
require_relative '../utils/vertex'
### 广度优先遍历 ###
def graph_bfs(graph, start_vet)
# 使用邻接表来表示图,以便获取指定顶点的所有邻接顶点
# 顶点遍历序列
res = []
# 哈希表,用于记录已被访问过的顶点
visited = Set.new([start_vet])
# 队列用于实现 BFS
que = [start_vet]
# 以顶点 vet 为起点,循环直至访问完所有顶点
while que.length > 0
vet = que.shift # 队首顶点出队
res << vet # 记录访问顶点
# 遍历该顶点的所有邻接顶点
for adj_vet in graph.adj_list[vet]
next if visited.include?(adj_vet) # 跳过已被访问的顶点
que << adj_vet # 只入队未访问的顶点
visited.add(adj_vet) # 标记该顶点已被访问
end
end
# 返回顶点遍历序列
res
end
### Driver Code ###
if __FILE__ == $0
# 初始化无向图
v = vals_to_vets([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
edges = [
[v[0], v[1]],
[v[0], v[3]],
[v[1], v[2]],
[v[1], v[4]],
[v[2], v[5]],
[v[3], v[4]],
[v[3], v[6]],
[v[4], v[5]],
[v[4], v[7]],
[v[5], v[8]],
[v[6], v[7]],
[v[7], v[8]],
]
graph = GraphAdjList.new(edges)
puts "\n初始化后,图为"
graph.__print__
# 广度优先遍历
res = graph_bfs(graph, v.first)
puts "\n广度优先便利BFS顶点序列为"
p vets_to_vals(res)
end