Python program to implement Breadth first search Traversal.

from collections import defaultdict
class Graph:

	def __init__(self):

		self.graph = defaultdict(list)

	def addEdge(self,u,v):
		self.graph[u].append(v)

	def BFS(self, s):

		visited = [False]*(len(self.graph))

		queue = []
		queue.append(s)
		visited[s] = True

		while queue:

			s = queue.pop(0)
			print (s)
			for i in self.graph[s]:
				if visited[i] == False:
					queue.append(i)
					visited[i] = True


g = Graph()
g.addEdge(0, 1)
g.addEdge(0, 2)
g.addEdge(1, 2)
g.addEdge(2, 0)
g.addEdge(2, 3)
g.addEdge(3, 3)
g.BFS(2)