Question

A graph consists of nodes and edges. An edge is an (unordered) pair of two distinct nodes in the graph. We create a new empty graph from the class Graph. We use the add_node method to add a single node and the add_nodes method to add multiple nodes. Nodes are identified by unique symbols. We call add_edge with two nodes to add an edge between a pair of nodes belonging to the graph. We can also ask a graph for the number of nodes and edges it contains, and for a list of its nodes and edges. The to_s method returns a string representing the graph's adjacency lists. Methods should not change the graph if called with invalid arguments; e.g., adding an edge that is already in the graph or that references a node that does not already belong to the graph. Your code does not have to generate the exact transcript that follows but it should provide this basic functionality.

>> g = Graph.new
=> 
>> g.add_node(:a)
=> a

>> g.add_nodes([:b, :c]) => [:b, :c]
>> g
=>

>> g.get_nodes
=> [:a, :b, :c]
>> g.nbr_nodes
=> 3

>> g.add_edge(:a, :b) => [a, b]
>> g.add_edge(:b, :c) => [b, c]

>> g
=> 
>> g.get_edges
=> [[a, b], [b, c]]

>> g.nbr_edges
=> 2
>> puts g
a -> b

b -> a,c
c -> b
=> nil

please I want the code in( Ruby) not another language

Answer 1

Option Infer On

Imports System
Imports System.Collections.Generic
Imports Microsoft.VisualBasic

Public Class Graph 'Assuming a directed graph
Private edges As New SortedDictionary(Of Char,List(Of Char))() 'A map to maintain the edges
Private nodes As New SortedSet(Of Char)() 'A set to maintain nodes, avoiding duplicacy
Private edge_count As Integer 'variable to keep track of number of edges
Public Sub add_node(ByVal node As Char)
nodes.Add(node) 'Inserting node to set
End Sub
Public Sub add_nodes(ByVal vNodes As List(Of Char))
For Each node As Char In vNodes
nodes.Add(node)
Next node
End Sub
Public Function add_edge(ByVal u As Char, ByVal v As Char) As Boolean
'Checking if both the entered nodes are valid and exists in the set of nodes
If nodes.find(u)=nodes.end() OrElse nodes.find(v)=nodes.end() Then
Return False
End If
edges(u).Add(v)
edge_count += 1
Return True
End Function
Public Function nbr_nodes() As Integer
Return CInt(nodes.Count)
End Function
Public Function nbr_edges() As Integer
Return edge_count
End Function
Public Function get_nodes() As String
Dim stringOfNodes As String
For Each node As Char In nodes
stringOfNodes.push_back(node) 'Generating string representation of the set of nodes
stringOfNodes &= ","
Next node
stringOfNodes.pop_back() 'Popping the extra , appened at the end
Return stringOfNodes
End Function
Public Function get_edges() As String
Dim stringOfEdges As String
For Each it In edges 'Iterating through each entry of edges map [Key]
For Each adj In it.second 'Iterating through the vector associated with each entry of the map [Value]
stringOfEdges &= "["
stringOfEdges.push_back(it.first)
stringOfEdges &= ","
stringOfEdges.push_back(adj)
stringOfEdges &= "],"
Next adj
Next it
stringOfEdges.pop_back()
Return stringOfEdges
End Function
Public Function to_s() As String
'Generating a string representation of the adjacency lists
Dim adjacencyString As String
For Each it In edges
adjacencyString.push_back(it.first)
adjacencyString &= " -> "
For Each adj In it.second
adjacencyString.push_back(adj)
adjacencyString &= ","
Next adj
adjacencyString.pop_back()
adjacencyString &= vbLf
Next it
Return adjacencyString
End Function
End Class

Public Class GlobalMembers
'Code for testing
Shared Function Main() As Integer
Dim g As New Graph()
g.add_node("a"c)
g.add_nodes(New List(Of Char)() From {"b"c, "c"c})
Console.Write(g.get_nodes())
Console.Write(vbLf)
Console.Write(g.nbr_nodes())
Console.Write(vbLf)
g.add_edge("a"c, "b"c)
g.add_edge("b"c, "c"c)
Console.Write(g.get_edges())
Console.Write(vbLf)
Console.Write(g.nbr_edges())
Console.Write(vbLf)
Console.Write(g.to_s())
End Function
End Class