Exercise: Graph Implementation

class Graph:
    def __init__(self):
        self.numberOfNodes = 0
        self.adjacentList = {}

    def addVertex(self, node):
        self.adjacentList[node] = []
        self.numberOfNodes += 1
        
    def addEdge(self, node1, node2):
        # Undirected graph
        self.adjacentList[node1].append(node2)
        self.adjacentList[node2].append(node1)
    
    def showConnections(self):
        allNodes = self.adjacentList.keys()
        for node in allNodes:
            nodeConnections = self.adjacentList[node]
            connections = ""
            for vertex in nodeConnections:
                connections += vertex + " "
            print(node + "-->" + connections)

myGraph = Graph()
myGraph.addVertex('0')
myGraph.addVertex('1')
myGraph.addVertex('2')
myGraph.addVertex('3')
myGraph.addVertex('4')
myGraph.addVertex('5')
myGraph.addVertex('6')
myGraph.addEdge('3', '1')
myGraph.addEdge('3', '4')
myGraph.addEdge('4', '2')
myGraph.addEdge('4', '5')
myGraph.addEdge('1', '2')
myGraph.addEdge('1', '0')
myGraph.addEdge('0', '2')
myGraph.addEdge('6', '5')

myGraph.showConnections()
# Answer:
# 0-->1 2 
# 1-->3 2 0 
# 2-->4 1 0 
# 3-->1 4 
# 4-->3 2 5 
# 5-->4 6 
# 6-->5