# the program below implements the above graph using two functions namely add_edge to add edges to the graph and show_graph to show all the edges in the graph.

class Graph:

graph_dict={}

def addEdge(self,node,neighbour):

if node not in self.graph_dict:

self.graph_dict[node]=[neighbour]

else:

self.graph_dict[node].append(neighbour)

def show_edges(self):

for node in self.graph_dict:

for neighbour in self.graph_dict[node]:

print("(",node,", ",neighbour,")")

# paths between two nodes.

def find_path(self,start,end,path=[]):

path = path + [start]

if start==end:

return path

'''Loop for transversing all neighbouring nodes of the start node and then recursively calls itself again untill finds a path from one node to the end node. '''

for node in self.graph_dict[start]:

if node not in path:

newPath=self.find_path(node,end,path)

if newPath:

return newPath

return None

g= Graph()

#inputs for the graphs nodes. i took pre defined nodes for easy observation of adjacent nodes.

g.addEdge('1', '2')

g.addEdge('1', '3')

g.addEdge('2', '3')

g.addEdge('2', '1')

g.addEdge('3', '1')

g.addEdge('3', '2')

g.addEdge('3', '4')

g.addEdge('4', '3')

g.show_edges()

print(g.find_path('4', '1'))

'''

The output of the graph will be the same as the input we provided it -

( 1 , 2 )

( 1 , 3 )

( 2 , 3 )

( 2 , 1 )

( 3 , 1 )

( 3 , 2 )

( 3 , 4 )

( 4 , 3 )

#path of the nodes transversal

[‘4’, ‘3’, ‘1’]

'''