## Python, graph, check_bipartite_graph_bfs.py

``````# Check whether Graph is Bipartite or Not using BFS

# A Bipartite Graph is a graph whose vertices can be divided into two independent sets,
# U and V such that every edge (u, v) either connects a vertex from U to V or a vertex
# from V to U. In other words, for every edge (u, v), either u belongs to U and v to V,
# or u belongs to V and v to U. We can also say that there is no edge that connects
# vertices of same set.
from queue import Queue

def checkBipartite(graph):
queue = Queue()
visited = [False] * len(graph)
color = [-1] * len(graph)

def bfs():
while not queue.empty():
u = queue.get()
visited[u] = True

for neighbour in graph[u]:

if neighbour == u:
return False

if color[neighbour] == -1:
color[neighbour] = 1 - color[u]
queue.put(neighbour)

elif color[neighbour] == color[u]:
return False

return True

for i in range(len(graph)):
if not visited[i]:
queue.put(i)
color[i] = 0
if bfs() is False:
return False

return True

if __name__ == "__main__":