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63 lines
1.5 KiB
63 lines
1.5 KiB
# Python3 Program to print BFS traversal
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from collections import defaultdict
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# This class represents a directed graph
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# using adjacency list representation
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class Graph:
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# Constructor
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def __init__(self):
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# default dictionary to store graph
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self.graph = defaultdict(list)
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# function to add an edge to graph
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def addEdge(self,u,v):
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self.graph[u].append(v)
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# Function to print a BFS of graph
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def BFS(self, s):
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# Mark all the vertices as not visited
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visited = [False] * (len(self.graph))
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# Create a queue for BFS
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queue = []
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# Mark the source node as
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# visited and enqueue it
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queue.append(s)
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visited[s] = True
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while queue:
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# Dequeue a vertex from
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# queue and print it
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s = queue.pop(0)
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print (s, end = " ")
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# Get all adjacent vertices of the
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# dequeued vertex s. If a adjacent
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# has not been visited, then mark it
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# visited and enqueue it
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for i in self.graph[s]:
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if visited[i] == False:
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queue.append(i)
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visited[i] = True
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# Driver code
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g = Graph()
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g.addEdge(0, 1)
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g.addEdge(0, 2)
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g.addEdge(1, 2)
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g.addEdge(2, 0)
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g.addEdge(2, 3)
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g.addEdge(3, 3)
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print ("Following is Breadth First Traversal"
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" (starting from vertex 2)")
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g.BFS(2)
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