system-design-primer/solutions/system_design/social_graph/social_graph_snippets.py

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2017-03-05 12:06:28 +07:00
# -*- coding: utf-8 -*-
from collections import deque
from enum import Enum
class State(Enum):
unvisited = 0
visited = 1
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class Graph(object):
def bfs(self, source, dest):
if source is None:
return False
queue = deque()
queue.append(source)
source.visit_state = State.visited
while queue:
node = queue.popleft()
print(node)
if dest is node:
return True
for adjacent_node in node.adj_nodes.values():
if adjacent_node.visit_state == State.unvisited:
queue.append(adjacent_node)
adjacent_node.visit_state = State.visited
return False
class Person(object):
def __init__(self, id, name):
self.id = id
self.name = name
self.friend_ids = []
class LookupService(object):
def __init__(self):
self.lookup = {} # key: person_id, value: person_server
def get_person(self, person_id):
person_server = self.lookup[person_id]
return person_server.people[person_id]
class PersonServer(object):
def __init__(self):
self.people = {} # key: person_id, value: person
def get_people(self, ids):
results = []
for id in ids:
if id in self.people:
results.append(self.people[id])
return results
class UserGraphService(object):
def __init__(self, person_ids, lookup):
self.lookup = lookup
self.person_ids = person_ids
self.visited_ids = set()
def bfs(self, source, dest):
# Use self.visited_ids to track visited nodes
# Use self.lookup to translate a person_id to a Person
pass