Python-广度优先搜索

如图所示：

?

以此图为例寻找末尾为“m”的名称。这里使用广度优先搜索，这个可以回答两类问题：

第一类问题：从节点A出发，有前往节点B的路径吗？

第二类问题：从节点A出发，前往节点B的哪条路径最短？

那这里其实就是寻找末尾为“m”名称的最短路径。

from collections import deque


def person_is_seller(name):
    return name[-1] == ‘m‘

graph = {}
graph["you"] = ["alice","bob","claire"]
graph["bob"] = ["anuj","peggy"]
graph["alice"] = ["peggy"]
graph["claire"] = ["thom","jonny"]
graph["anuj"] = []
graph["peggy"] = []
graph["thom"] = []
graph["jonny"] = []

def search(name):
    search_queue = deque()
    search_queue += graph[name]
    searched = []
    while search_queue:
        person = search_queue.popleft()
        if person not in searched:
            if person_is_seller(person):
                print(person + ‘ is a mongo seller‘)
                return True
            else:
                search_queue += graph[person]
                searched.append(person)
    return False

search("you")

这里使用到了散列表的概念，以及Python中deque函数来创建一个双端队列。?