Python Graph implementation

Author: OmkarPathak

data_structures/Graph/Graph.py

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+# Author: OMKAR PATHAK
+
+# We can use Python's dictionary for constructing the graph
+
+classAdjacencyList(object):
+def__init__(self):
+self.List={}
+
+defaddEdge(self, fromVertex, toVertex):
+# check if vertex is already present
+iffromVertexinself.List.keys():
+self.List[fromVertex].append(toVertex)
+else:
+self.List[fromVertex] = [toVertex]
+
+defprintList(self):
+foriinself.List:
+print(i,'->',' -> '.join([str(j) forjinself.List[i]]))
+
+if__name__=='__main__':
+al=AdjacencyList()
+al.addEdge(0, 1)
+al.addEdge(0, 4)
+al.addEdge(4, 1)
+al.addEdge(4, 3)
+al.addEdge(1, 0)
+al.addEdge(1, 4)
+al.addEdge(1, 3)
+al.addEdge(1, 2)
+al.addEdge(2, 3)
+al.addEdge(3, 4)
+
+al.printList()
+
+# OUTPUT:
+# 0 -> 1 -> 4
+# 1 -> 0 -> 4 -> 3 -> 2
+# 2 -> 3
+# 3 -> 4
+# 4 -> 1 -> 3

data_structures/Graph/P01_BreadthFirstSearch.py

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+# Author: OMKAR PATHAK
+
+classGraph():
+def__init__(self):
+self.vertex={}
+
+# for printing the Graph vertexes
+defprintGraph(self):
+foriinself.vertex.keys():
+print(i,' -> ', ' -> '.join([str(j) forjinself.vertex[i]]))
+
+# for adding the edge beween two vertexes
+defaddEdge(self, fromVertex, toVertex):
+# check if vertex is already present,
+iffromVertexinself.vertex.keys():
+self.vertex[fromVertex].append(toVertex)
+else:
+# else make a new vertex
+self.vertex[fromVertex] = [toVertex]
+
+defBFS(self, startVertex):
+# Take a list for stoting already visited vertexes
+visited= [False] *len(self.vertex)
+
+# create a list to store all the vertexes for BFS
+queue= []
+
+# mark the source node as visited and enqueue it
+visited[startVertex] =True
+queue.append(startVertex)
+
+whilequeue:
+startVertex=queue.pop(0)
+print(startVertex, end=' ')
+
+# mark all adjacent nodes as visited and print them
+foriinself.vertex[startVertex]:
+ifvisited[i] ==False:
+queue.append(i)
+visited[i] =True
+
+if__name__=='__main__':
+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.printGraph()
+print('BFS:')
+g.BFS(2)
+
+# OUTPUT:
+# 0 -> 1 -> 2
+# 1 -> 2
+# 2 -> 0 -> 3
+# 3 -> 3
+# BFS:
+# 2 0 3 1

data_structures/Graph/P02_DepthFirstSearch.py

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+# Author: OMKAR PATHAK
+
+classGraph():
+def__init__(self):
+self.vertex={}
+
+# for printing the Graph vertexes
+defprintGraph(self):
+print(self.vertex)
+foriinself.vertex.keys():
+print(i,' -> ', ' -> '.join([str(j) forjinself.vertex[i]]))
+
+# for adding the edge beween two vertexes
+defaddEdge(self, fromVertex, toVertex):
+# check if vertex is already present,
+iffromVertexinself.vertex.keys():
+self.vertex[fromVertex].append(toVertex)
+else:
+# else make a new vertex
+self.vertex[fromVertex] = [toVertex]
+
+defDFS(self):
+# visited array for storing already visited nodes
+visited= [False] *len(self.vertex)
+
+# call the recursive helper function
+foriinrange(len(self.vertex)):
+ifvisited[i] ==False:
+self.DFSRec(i, visited)
+
+defDFSRec(self, startVertex, visited):
+# mark start vertex as visited
+visited[startVertex] =True
+
+print(startVertex, end=' ')
+
+# Recur for all the vertexes that are adjacent to this node
+foriinself.vertex.keys():
+ifvisited[i] ==False:
+self.DFSRec(i, visited)
+
+if__name__=='__main__':
+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.printGraph()
+print('DFS:')
+g.DFS()
+
+# OUTPUT:
+# 0 -> 1 -> 2
+# 1 -> 2
+# 2 -> 0 -> 3
+# 3 -> 3
+# DFS:
+# 0 1 2 3