graph.py

# Graph implementation in python 
# adjacency list representation

class Graph:
	def __init__(self, no_of_nodes):
		self.n = no_of_nodes
		self.al = []
		for i in range(no_of_nodes): 
			self.al.append(list())
			
	def add_edge(self, x, y):
		if x < len(self.al) and y < len(self.al):
			self.al[x].append(y)
			self.al[y].append(x)
	
	def print_graph(self):
		i = 0
		for node in self.al:
			print(i, '->', node)
			i = i + 1

def run():
	g = Graph(5)
	g.add_edge(0,1)
	g.add_edge(0, 2)
	g.add_edge(0, 3)
	g.print_graph()

if __name__ == "__main__":
	run()