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* Update queue implementation Popping the first element of a list takes O(n) time. Using a cyclic queue takes O(1) time. * Add queue changes from extra files * Update indentation * Add empty line between imports * Fix lines * Apply suggestions from code review Co-authored-by: John Law <johnlaw.po@gmail.com> Co-authored-by: John Law <johnlaw.po@gmail.com>
49 lines
1.3 KiB
Python
49 lines
1.3 KiB
Python
# Check whether Graph is Bipartite or Not using BFS
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# A Bipartite Graph is a graph whose vertices can be divided into two independent sets,
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# U and V such that every edge (u, v) either connects a vertex from U to V or a vertex
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# from V to U. In other words, for every edge (u, v), either u belongs to U and v to V,
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# or u belongs to V and v to U. We can also say that there is no edge that connects
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# vertices of same set.
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from queue import Queue
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def checkBipartite(graph):
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queue = Queue()
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visited = [False] * len(graph)
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color = [-1] * len(graph)
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def bfs():
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while not queue.empty():
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u = queue.get()
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visited[u] = True
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for neighbour in graph[u]:
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if neighbour == u:
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return False
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if color[neighbour] == -1:
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color[neighbour] = 1 - color[u]
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queue.put(neighbour)
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elif color[neighbour] == color[u]:
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return False
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return True
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for i in range(len(graph)):
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if not visited[i]:
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queue.put(i)
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color[i] = 0
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if bfs() is False:
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return False
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return True
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if __name__ == "__main__":
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# Adjacency List of graph
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print(checkBipartite({0: [1, 3], 1: [0, 2], 2: [1, 3], 3: [0, 2]}))
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