BFS Examples
from collections import deque
#
# 1. We create a search queue and add the starting vertex to it.
# 2. We mark the starting vertex as searched.
# 3. We loop through the queue.
# 4. We get the next person from the queue and then we check if they’re a mango seller.
# 5. If they are, we print out that they are a mango seller and return.
# 6. If they aren’t, we add all of their neighbors to the search queue.
# 7. We mark the person as searched.
# 8. We keep looping until the queue is empty.
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]
# This is how you keep track of which people you've searched before.
searched = set()
while search_queue:
person = search_queue.popleft()
# Only search this person if you haven't already searched them.
if person not in searched:
if person_is_seller(person):
print(person + " is a mango seller!")
return True
else:
search_queue += graph[person]
# Marks this person as searched
searched.add(person)
return False
search("you")
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