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Code Graph

Reverse delete algorithm for minimum spanning tree

The reverse delete algorithm is a method used to find the minimum spanning tree of a graph, where the minimum spanning tree is a subset of edges that connects all the vertices with the minimum possible total edge weight. This article presents a detailed explanation of the reverse delete algorithm and provides a Java code implementation to demonstrate its application.

Example Reverse delete algorithm minimum spanning tree

Problem Statement

Given an undirected graph with weighted edges, the goal is to find the minimum spanning tree by iteratively removing edges while maintaining the connectivity of the graph.

Description with Example

Imagine a scenario where you have a set of cities connected by roads with varying lengths. The reverse delete algorithm can help you identify the roads that need to be retained to ensure that all cities remain connected while minimizing the total road length.

Idea to Solve

The reverse delete algorithm works by first sorting the edges of the graph in decreasing order of their weights. It then iteratively removes edges from the highest weight to the lowest while checking if the graph remains connected after each removal.

Pseudocode

function reverseDeleteMST(graph):
    result = 0
    point = graph.edges
    while point is not null:
        remove edge (point.u, point.v) from the graph
        if graph is still connected:
            add edge (point.u, point.v) back to the graph
            update result by adding point's weight
            print edge (point.u, point.v)
        point = point.next
    print total weight of MST: result

Algorithm Explanation

  1. Initialize the result variable to store the total weight of the minimum spanning tree.
  2. Initialize the point variable to the first edge in the sorted list of edges.
  3. Iterate through each edge: a. Remove the edge (u, v) from the graph. b. Check if the graph remains connected using the isConnected function. c. If the graph is still connected:
    • Add the edge (u, v) back to the graph.
    • Update the result by adding the weight of the edge.
    • Print the edge (u, v) to indicate it's part of the MST. d. Move to the next edge.
  4. Print the total weight of the minimum spanning tree: result.

Program solution

import java.util.ArrayList;
/*
    Java Program
    Reverse delete algorithm for minimum spanning tree
*/
class Edge
{
	// edge weight or cost  
	public int weight;
	public int u;
	public int v;
	public Edge next;
	public Edge(int weight, int u, int v)
	{
		this.weight = weight;
		this.u = u;
		this.v = v;
		this.next = null;
	}
}
public class Graph
{
	public int vertices;
	public ArrayList < ArrayList < Integer >> adgeList;
	public Edge edges;
	public int edgeCount;
	public Graph(int vertices)
	{
		this.vertices = vertices;
		this.adgeList = new ArrayList < ArrayList < Integer >> (vertices);
		this.edges = null;
		this.edgeCount = 0;
		for (int i = 0; i < this.vertices; ++i)
		{
			this.adgeList.add(new ArrayList < Integer > ());
		}
	}
	public void addEdge(int u, int v, int w)
	{
		if (u < 0 || u >= this.vertices || v < 0 || v >= this.vertices)
		{
			return;
		}
      	// add node edge
		adgeList.get(u).add(v);
		adgeList.get(v).add(u);
      	// Collect descending order sorted edges
		// Create new edge
		Edge e = new Edge(w, u, v);
		// Add edge in decreasing order
		if (this.edges == null)
		{
			// First edge
			this.edges = e;
		}
		else if (this.edges.weight <= e.weight)
		{
			// Add edges in front
			e.next = this.edges;
			this.edges = e;
		}
		else
		{
			Edge temp = this.edges;
			// Find position to add new edge
			while (temp.next != null && temp.next.weight > e.weight)
			{
				temp = temp.next;
			}
			e.next = temp.next;
			temp.next = e;
		}
		this.edgeCount = this.edgeCount + 1;
	}
	// Perform DFS
	public void findDFS(int v, boolean[] visited)
	{
		// Indicates the current vertex is visited
		visited[v] = true;
		// iterate edges of v node
		for (int i = 0; i < this.adgeList.get(v).size(); i++)
		{
			if (visited[this.adgeList.get(v).get(i)] == false)
			{
				findDFS(this.adgeList.get(v).get(i), visited);
			}
		}
	}
	// Check that graph start vertices are reach to all other vertices or not
	public boolean isConnected()
	{
		boolean[] visited = new boolean[this.vertices];
		// Set the initial visited vertices
		for (int i = 0; i < this.vertices; ++i)
		{
			visited[i] = false;
		}
		this.findDFS(0, visited);
		for (int i = 1; i < this.vertices; i++)
		{
			if (visited[i] == false)
			{
				// When [i] vertices are not visit
				return false;
			}
		}
		return true;
	}
	public void printGraph()
	{
      	System.out.print("\n Graph Adjacency List ");
		for (int i = 0; i < this.vertices; ++i)
		{
			System.out.print(" \n [" + i + "] :");
			// iterate edges of i node
			for (int j = 0; j < this.adgeList.get(i).size(); j++)
			{
				System.out.print("  " + this.adgeList.get(i).get(j));
			}
		}
	}
	public void reverseDeleteMST()
	{
		int result = 0;
		// Get first higher edge
		Edge point = this.edges;
		System.out.println("\n\nConnected node by Edges in MST");
		// iterates the edge from high to low order
		while (point != null)
		{
			// Remove the current weight edge of node from u to v and v to u
			adgeList.get(point.u).remove(new Integer(point.v));
			adgeList.get(point.v).remove(new Integer(point.u));
			if (isConnected() == false)
			{
				// When delete edge are create problems (). 
				// Then they are add back into graph
				adgeList.get(point.u).add(point.v);
				adgeList.get(point.v).add(point.u);
				// Update weight    
				result += point.weight;
				// Display edge
				System.out.print(" (" + point.u + ", " + point.v + ") \n");
			}
			// Visit next smaller weight edge
			point = point.next;
		}
		System.out.println("Calculated total weight of MST is " + result);
	}
	public static void main(String[] args)
	{
		Graph g = new Graph(8);
		g.addEdge(0, 1, 5);
		g.addEdge(0, 3, 3);
		g.addEdge(1, 2, 3);
		g.addEdge(1, 6, 7);
		g.addEdge(1, 7, 9);
		g.addEdge(2, 5, 9);
		g.addEdge(2, 7, 4);
		g.addEdge(3, 4, 11);
		g.addEdge(3, 7, 8);
		g.addEdge(4, 5, 8);
		g.addEdge(4, 6, 14);
		g.addEdge(4, 7, 10);
		g.addEdge(5, 6, 11);
		// Display graph element
		g.printGraph();
		// Find MST
		g.reverseDeleteMST();
	}
}

input

 Graph Adjacency List
 [0] :  1  3
 [1] :  0  2  6  7
 [2] :  1  5  7
 [3] :  0  4  7
 [4] :  3  5  6  7
 [5] :  2  4  6
 [6] :  1  4  5
 [7] :  1  2  3  4

Connected node by Edges in MST
 (2, 5)
 (4, 5)
 (1, 6)
 (0, 1)
 (2, 7)
 (1, 2)
 (0, 3)
Calculated total weight of MST is 39
// Include header file
#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;
/*
    C++ Program
    Reverse delete algorithm for minimum spanning tree
*/
class Edge
{
    public:
    // edge weight or cost  
    int weight;
    int u;
    int v;
    Edge *next;
    Edge(int weight, int u, int v)
    {
        this->weight = weight;
        this->u = u;
        this->v = v;
        this->next = NULL;
    }
};
class Graph
{
    public: int vertices;
    vector <vector<int> > adgeList;
    Edge *edges;
    int edgeCount;
    Graph(int vertices)
    {
        this->vertices = vertices;
        this->edges = NULL;
        this->edgeCount = 0;
        for(int i = 0 ; i < vertices; ++i)
        {
            this->adgeList.push_back(vector<int>());
        }
    }
    void addEdge(int u, int v, int w)
    {
        if (u < 0 || u >= this->vertices || v < 0 || v >= this->vertices)
        {
            return;
        }
        // add node edge
        this->adgeList.at(u).push_back(v);
        this->adgeList.at(v).push_back(u);
        // Collect descending order sorted edges
        // Create new edge
        Edge *e = new Edge(w, u, v);
        // Add edge in decreasing order
        if (this->edges == NULL)
        {
            // First edge
            this->edges = e;
        }
        else if (this->edges->weight <= e->weight)
        {
            // Add edges in front
            e->next = this->edges;
            this->edges = e;
        }
        else
        {
            Edge *temp = this->edges;
            // Find position to add new edge
            while (temp->next != NULL && temp->next->weight > e->weight)
            {
                temp = temp->next;
            }
            e->next = temp->next;
            temp->next = e;
        }
        this->edgeCount = this->edgeCount + 1;
    }
    // Perform DFS
    void findDFS(int v, bool visited[])
    {
        // Indicates the current vertex is visited
        visited[v] = true;
        // iterate edges of v node
        for (int i = 0; i < this->adgeList.at(v).size(); i++)
        {
            if (visited[this->adgeList.at(v).at(i)] == false)
            {
                this->findDFS(this->adgeList.at(v).at(i), visited);
            }
        }
    }
    // Check that graph start vertices are reach to all other vertices or not
    bool isConnected()
    {
        bool visited[this->vertices];
        // Set the initial visited vertices
        for (int i = 0; i < this->vertices; ++i)
        {
            visited[i] = false;
        }
        this->findDFS(0, visited);
        for (int i = 1; i < this->vertices; i++)
        {
            if (visited[i] == false)
            {
                // When [i] vertices are not visit
                return false;
            }
        }
        return true;
    }
    void printGraph()
    {
        cout << "\n Graph Adjacency List ";
        for (int i = 0; i < this->vertices; ++i)
        {
            cout << " \n [" << i << "] :";
            // iterate edges of i node
            for (int j = 0; j < this->adgeList.at(i).size(); j++)
            {
                cout << "  " << this->adgeList.at(i).at(j);
            }
        }
    }
    void reverseDeleteMST()
    {
        int result = 0;
        // Get first higher edge
        Edge *point = this->edges;
        cout << "\n\nConnected node by Edges in MST" << endl;
        // iterates the edge from high to low order
        while (point != NULL)
        {
          
           
            // Remove the current weight edge of node from u to v and v to u
            this->adgeList.at(point->u).erase(remove(this->adgeList.at(point->u).begin(), this->adgeList.at(point->u).end(), point->v), this->adgeList.at(point->u).end());
            this->adgeList.at(point->v).erase(remove(this->adgeList.at(point->v).begin(), this->adgeList.at(point->v).end(), point->u), this->adgeList.at(point->v).end());

            if (this->isConnected() == false)
            {
                // When delete edge are create problems (). 
                // Then they are add back into graph
                this->adgeList.at(point->u).push_back(point->v);
                this->adgeList.at(point->v).push_back(point->u);
                // Update weight    
                result += point->weight;
                // Display edge
                cout << " (" << point->u << ", " << point->v << ") \n";
            }
            // Visit next smaller weight edge
            point = point->next;
        }
        cout << "Calculated total weight of MST is " << result << endl;
    }
};
int main()
{
    Graph *g = new Graph(8);
    g->addEdge(0, 1, 5);
    g->addEdge(0, 3, 3);
    g->addEdge(1, 2, 3);
    g->addEdge(1, 6, 7);
    g->addEdge(1, 7, 9);
    g->addEdge(2, 5, 9);
    g->addEdge(2, 7, 4);
    g->addEdge(3, 4, 11);
    g->addEdge(3, 7, 8);
    g->addEdge(4, 5, 8);
    g->addEdge(4, 6, 14);
    g->addEdge(4, 7, 10);
    g->addEdge(5, 6, 11);
    // Display graph element
    g->printGraph();
    // Find MST
    g->reverseDeleteMST();
    return 0;
}

input

 Graph Adjacency List
 [0] :  1  3
 [1] :  0  2  6  7
 [2] :  1  5  7
 [3] :  0  4  7
 [4] :  3  5  6  7
 [5] :  2  4  6
 [6] :  1  4  5
 [7] :  1  2  3  4

Connected node by Edges in MST
 (2, 5)
 (4, 5)
 (1, 6)
 (0, 1)
 (2, 7)
 (1, 2)
 (0, 3)
Calculated total weight of MST is 39
// Include namespace system
using System;
using System.Collections.Generic;
/*
    Csharp Program
    Reverse delete algorithm for minimum spanning tree
*/
public class Edge
{
	// edge weight or cost  
	public int weight;
	public int u;
	public int v;
	public Edge next;
	public Edge(int weight, int u, int v)
	{
		this.weight = weight;
		this.u = u;
		this.v = v;
		this.next = null;
	}
}
public class Graph
{
	public int vertices;
	public List < List < int >> adgeList;
	public Edge edges;
	public int edgeCount;
	public Graph(int vertices)
	{
		this.vertices = vertices;
		this.adgeList = new List < List < int >> (vertices);
		this.edges = null;
		this.edgeCount = 0;
		for (int i = 0; i < this.vertices; ++i)
		{
			this.adgeList.Add(new List < int > ());
		}
	}
	public void addEdge(int u, int v, int w)
	{
		if (u < 0 || u >= this.vertices || v < 0 || v >= this.vertices)
		{
			return;
		}
		// add node edge
		this.adgeList[u].Add(v);
		this.adgeList[v].Add(u);
		// Collect descending order sorted edges
		// Create new edge
		Edge e = new Edge(w, u, v);
		// Add edge in decreasing order
		if (this.edges == null)
		{
			// First edge
			this.edges = e;
		}
		else if (this.edges.weight <= e.weight)
		{
			// Add edges in front
			e.next = this.edges;
			this.edges = e;
		}
		else
		{
			Edge temp = this.edges;
			// Find position to add new edge
			while (temp.next != null && temp.next.weight > e.weight)
			{
				temp = temp.next;
			}
			e.next = temp.next;
			temp.next = e;
		}
		this.edgeCount = this.edgeCount + 1;
	}
	// Perform DFS
	public void findDFS(int v, Boolean[] visited)
	{
		// Indicates the current vertex is visited
		visited[v] = true;
		// iterate edges of v node
		for (int i = 0; i < this.adgeList[v].Count; i++)
		{
			if (visited[this.adgeList[v][i]] == false)
			{
				this.findDFS(this.adgeList[v][i], visited);
			}
		}
	}
	// Check that graph start vertices are reach to all other vertices or not
	public Boolean isConnected()
	{
		Boolean[] visited = new Boolean[this.vertices];
		// Set the initial visited vertices
		for (int i = 0; i < this.vertices; ++i)
		{
			visited[i] = false;
		}
		this.findDFS(0, visited);
		for (int i = 1; i < this.vertices; i++)
		{
			if (visited[i] == false)
			{
				// When [i] vertices are not visit
				return false;
			}
		}
		return true;
	}
	public void printGraph()
	{
		Console.Write("\n Graph Adjacency List ");
		for (int i = 0; i < this.vertices; ++i)
		{
			Console.Write(" \n [" + i + "] :");
			// iterate edges of i node
			for (int j = 0; j < this.adgeList[i].Count; j++)
			{
				Console.Write("  " + this.adgeList[i][j]);
			}
		}
	}
	public void reverseDeleteMST()
	{
		int result = 0;
		// Get first higher edge
		Edge point = this.edges;
		Console.WriteLine("\n\nConnected node by Edges in MST");
		// iterates the edge from high to low order
		while (point != null)
		{
			// Remove the current weight edge of node from u to v and v to u
			this.adgeList[point.u].Remove(point.v);
			this.adgeList[point.v].Remove(point.u);
			if (this.isConnected() == false)
			{
				// When delete edge are create problems (). 
				// Then they are add back into graph
				this.adgeList[point.u].Add(point.v);
				this.adgeList[point.v].Add(point.u);
				// Update weight    
				result += point.weight;
				// Display edge
				Console.Write(" (" + point.u + ", " + point.v + ") \n");
			}
			// Visit next smaller weight edge
			point = point.next;
		}
		Console.WriteLine("Calculated total weight of MST is " + result);
	}
	public static void Main(String[] args)
	{
		Graph g = new Graph(8);
		g.addEdge(0, 1, 5);
		g.addEdge(0, 3, 3);
		g.addEdge(1, 2, 3);
		g.addEdge(1, 6, 7);
		g.addEdge(1, 7, 9);
		g.addEdge(2, 5, 9);
		g.addEdge(2, 7, 4);
		g.addEdge(3, 4, 11);
		g.addEdge(3, 7, 8);
		g.addEdge(4, 5, 8);
		g.addEdge(4, 6, 14);
		g.addEdge(4, 7, 10);
		g.addEdge(5, 6, 11);
		// Display graph element
		g.printGraph();
		// Find MST
		g.reverseDeleteMST();
	}
}

input

 Graph Adjacency List
 [0] :  1  3
 [1] :  0  2  6  7
 [2] :  1  5  7
 [3] :  0  4  7
 [4] :  3  5  6  7
 [5] :  2  4  6
 [6] :  1  4  5
 [7] :  1  2  3  4

Connected node by Edges in MST
 (2, 5)
 (4, 5)
 (1, 6)
 (0, 1)
 (2, 7)
 (1, 2)
 (0, 3)
Calculated total weight of MST is 39
<?php
/*
    Php Program
    Reverse delete algorithm for minimum spanning tree
*/
class Edge
{
    // edge weight or cost  
    public $weight;
    public $u;
    public $v;
    public $next;
    public  function __construct($weight, $u, $v)
    {
        $this->weight = $weight;
        $this->u = $u;
        $this->v = $v;
        $this->next = NULL;
    }
}
class Graph
{
    public $vertices;
    public $adgeList;
    public $edges;
    public $edgeCount;
    public  function __construct($vertices)
    {
        $this->vertices = $vertices;
        $this->adgeList = array();
        $this->edges = NULL;
        $this->edgeCount = 0;
        for ($i = 0; $i < $this->vertices; ++$i)
        {
            $this->adgeList[$i] = array();
        }
    }
    public  function addEdge($u, $v, $w)
    {
        if ($u < 0 || $u >= $this->vertices || $v < 0 || $v >= $this->vertices)
        {
            return;
        }
        // add node edge
        $this->adgeList[$u][] = $v;
        $this->adgeList[$v][] = $u;
        // Collect descending order sorted edges
        // Create new edge
        $e = new Edge($w, $u, $v);
        // Add edge in decreasing order
        if ($this->edges == NULL)
        {
            // First edge
            $this->edges = $e;
        }
        else if ($this->edges->weight <= $e->weight)
        {
            // Add edges in front
            $e->next = $this->edges;
            $this->edges = $e;
        }
        else
        {
            $temp = $this->edges;
            // Find position to add new edge
            while ($temp->next != NULL && $temp->next->weight > $e->weight)
            {
                $temp = $temp->next;
            }
            $e->next = $temp->next;
            $temp->next = $e;
        }
        $this->edgeCount = $this->edgeCount + 1;
    }
    // Perform DFS
    public  function findDFS($v, &$visited)
    {
        // Indicates the current vertex is visited
        $visited[$v] = true;
  
        // iterate edges of v node
      	foreach ($this->adgeList[$v] as $key=>$value)
        {
            if ($visited[$value] == false)
            {
                $this->findDFS($value, $visited);
            }
        }
    }
    // Check that graph start vertices are reach to all other vertices or not
    public  function isConnected()
    {
        $visited = array_fill(0, $this->vertices, false);
        $this->findDFS(0, $visited);
        for ($i = 1; $i < $this->vertices; $i++)
        {
            if ($visited[$i] == false)
            {
                // When [i] vertices are not visit
                return false;
            }
        }
        return true;
    }
    public  function printGraph()
    {
        echo("\n Graph Adjacency List ");
        for ($i = 0; $i < $this->vertices; ++$i)
        {
            echo(" \n [".$i."] :");
            // iterate edges of i node
            for ($j = 0; $j < count($this->adgeList[$i]); $j++)
            {
                echo("  ".$this->adgeList[$i][$j]);
            }
        }
    }
    public  function reverseDeleteMST()
    {
        $result = 0;
        // Get first higher edge
        $point = $this->edges;
        echo("\n\nConnected node by Edges in MST"."\n");
        // iterates the edge from high to low order
        while ($point != NULL)
        {

            // Remove the current weight edge of node from u to v and v to u
            if (($key = array_search($point->v, 
                                     $this->adgeList[$point->u])) !== false) {

              	unset($this->adgeList[$point->u][$key]);
           
            }
                        
            if (($key = array_search($point->u, 
                                     $this->adgeList[$point->v])) !== false) {

              	unset($this->adgeList[$point->v][$key]);
            }
   
            if ($this->isConnected() == false )
            {
                // When delete edge are create problems (). 
                // Then they are add back into graph
                $this->adgeList[$point->u][] = $point->v;
                $this->adgeList[$point->v][] = $point->u;
                // Update weight    
                $result += $point->weight;
                // Display edge
                echo(" (".$point->u.
                    ", ".$point->v.
                    ") \n");
            }
            // Visit next smaller weight edge
            $point = $point->next;
        }
        echo("Calculated total weight of MST is ".$result.
            "\n");
    }
}

function main()
{
    $g = new Graph(8);
    $g->addEdge(0, 1, 5);
    $g->addEdge(0, 3, 3);
    $g->addEdge(1, 2, 3);
    $g->addEdge(1, 6, 7);
    $g->addEdge(1, 7, 9);
    $g->addEdge(2, 5, 9);
    $g->addEdge(2, 7, 4);
    $g->addEdge(3, 4, 11);
    $g->addEdge(3, 7, 8);
    $g->addEdge(4, 5, 8);
    $g->addEdge(4, 6, 14);
    $g->addEdge(4, 7, 10);
    $g->addEdge(5, 6, 11);
    // Display graph element
    $g->printGraph();
    // Find MST
    $g->reverseDeleteMST();
}
main();

input

 Graph Adjacency List
 [0] :  1  3
 [1] :  0  2  6  7
 [2] :  1  5  7
 [3] :  0  4  7
 [4] :  3  5  6  7
 [5] :  2  4  6
 [6] :  1  4  5
 [7] :  1  2  3  4

Connected node by Edges in MST
 (2, 5)
 (4, 5)
 (1, 6)
 (0, 1)
 (2, 7)
 (1, 2)
 (0, 3)
Calculated total weight of MST is 39
/*
    Node JS Program
    Reverse delete algorithm for minimum spanning tree
*/
class Edge
{
	constructor(weight, u, v)
	{
		this.weight = weight;
		this.u = u;
		this.v = v;
		this.next = null;
	}
}
class Graph
{
	constructor(vertices)
	{
		this.vertices = vertices;
		this.adgeList = [];
		this.edges = null;
		this.edgeCount = 0;
		for (var i = 0; i < this.vertices; ++i)
		{
			this.adgeList.push([]);
		}
	}
	addEdge(u, v, w)
	{
		if (u < 0 || u >= this.vertices || v < 0 || v >= this.vertices)
		{
			return;
		}
		// add node edge
		this.adgeList[u].push(v);
		this.adgeList[v].push(u);
		// Collect descending order sorted edges
		// Create new edge
		var e = new Edge(w, u, v);
		// Add edge in decreasing order
		if (this.edges == null)
		{
			// First edge
			this.edges = e;
		}
		else if (this.edges.weight <= e.weight)
		{
			// Add edges in front
			e.next = this.edges;
			this.edges = e;
		}
		else
		{
			var temp = this.edges;
			// Find position to add new edge
			while (temp.next != null && temp.next.weight > e.weight)
			{
				temp = temp.next;
			}
			e.next = temp.next;
			temp.next = e;
		}
		this.edgeCount = this.edgeCount + 1;
	}
	// Perform DFS
	findDFS(v, visited)
	{
		// Indicates the current vertex is visited
		visited[v] = true;
		// iterate edges of v node
		for (var i = 0; i < this.adgeList[v].length; i++)
		{
			if (visited[this.adgeList[v][i]] == false)
			{
				this.findDFS(this.adgeList[v][i], visited);
			}
		}
	}
	// Check that graph start vertices are reach to all other vertices or not
	isConnected()
	{
		var visited = Array(this.vertices).fill(false);
		this.findDFS(0, visited);
		for (var i = 1; i < this.vertices; i++)
		{
			if (visited[i] == false)
			{
				// When [i] vertices are not visit
				return false;
			}
		}
		return true;
	}
	printGraph()
	{
		process.stdout.write("\n Graph Adjacency List ");
		for (var i = 0; i < this.vertices; ++i)
		{
			process.stdout.write(" \n [" + i + "] :");
			// iterate edges of i node
			for (var j = 0; j < this.adgeList[i].length; j++)
			{
				process.stdout.write("  " + this.adgeList[i][j]);
			}
		}
	}
	reverseDeleteMST()
	{
		var result = 0;
		// Get first higher edge
		var point = this.edges;
		var index = 0;
		console.log("\n\nConnected node by Edges in MST");
		// iterates the edge from high to low order
		while (point != null)
		{
			// Remove the current weight edge of node from u to v and v to u
			index = this.adgeList[point.u].indexOf(point.v);
			if (index !== -1)
			{
				this.adgeList[point.u].splice(index, 1);
			}
			index = this.adgeList[point.v].indexOf(point.u);
			if (index !== -1)
			{
				this.adgeList[point.v].splice(index, 1);
			}
			if (this.isConnected() == false)
			{
				// When delete edge are create problems (). 
				// Then they are add back into graph
				this.adgeList[point.u].push(point.v);
				this.adgeList[point.v].push(point.u);
				// Update weight    
				result += point.weight;
				// Display edge
				process.stdout.write(" (" + point.u + ", " + point.v + ") \n");
			}
			// Visit next smaller weight edge
			point = point.next;
		}
		console.log("Calculated total weight of MST is " + result);
	}
}

function main()
{
	var g = new Graph(8);
	g.addEdge(0, 1, 5);
	g.addEdge(0, 3, 3);
	g.addEdge(1, 2, 3);
	g.addEdge(1, 6, 7);
	g.addEdge(1, 7, 9);
	g.addEdge(2, 5, 9);
	g.addEdge(2, 7, 4);
	g.addEdge(3, 4, 11);
	g.addEdge(3, 7, 8);
	g.addEdge(4, 5, 8);
	g.addEdge(4, 6, 14);
	g.addEdge(4, 7, 10);
	g.addEdge(5, 6, 11);
	// Display graph element
	g.printGraph();
	// Find MST
	g.reverseDeleteMST();
}
main();

input

 Graph Adjacency List
 [0] :  1  3
 [1] :  0  2  6  7
 [2] :  1  5  7
 [3] :  0  4  7
 [4] :  3  5  6  7
 [5] :  2  4  6
 [6] :  1  4  5
 [7] :  1  2  3  4

Connected node by Edges in MST
 (2, 5)
 (4, 5)
 (1, 6)
 (0, 1)
 (2, 7)
 (1, 2)
 (0, 3)
Calculated total weight of MST is 39
#    Python 3 Program
#    Reverse delete algorithm for minimum spanning tree
class Edge :
	#  edge weight or cost  
	def __init__(self, weight, u, v) :
		self.weight = weight
		self.u = u
		self.v = v
		self.next = None
	

class Graph :
	def __init__(self, vertices) :
		self.vertices = vertices
		self.adgeList = []
		self.edges = None
		self.edgeCount = 0
		i = 0
		while (i < self.vertices) :
			self.adgeList.append([])
			i += 1
		
	
	def addEdge(self, u, v, w) :
		if (u < 0 or u >= self.vertices or v < 0 or v >= self.vertices) :
			return
		
		#  add node edge
		self.adgeList[u].append(v)
		self.adgeList[v].append(u)
		#  Collect descending order sorted edges
		#  Create new edge
		e = Edge(w, u, v)
		#  Add edge in decreasing order
		if (self.edges == None) :
			#  First edge
			self.edges = e
		elif (self.edges.weight <= e.weight) :
			#  Add edges in front
			e.next = self.edges
			self.edges = e
		else :
			temp = self.edges
			#  Find position to add new edge
			while (temp.next != None and temp.next.weight > e.weight) :
				temp = temp.next
			
			e.next = temp.next
			temp.next = e
		
		self.edgeCount = self.edgeCount + 1
	
	#  Perform DFS
	def findDFS(self, v, visited) :
		#  Indicates the current vertex is visited
		visited[v] = True
		i = 0
		#  iterate edges of v node
		while (i < len(self.adgeList[v])) :
			if (visited[self.adgeList[v][i]] == False) :
				self.findDFS(self.adgeList[v][i], visited)
			
			i += 1
		
	
	#  Check that graph start vertices are reach to all other vertices or not
	def isConnected(self) :
		visited = [False] * (self.vertices)
		i = 0
		#  Set the initial visited vertices
		while (i < self.vertices) :
			visited[i] = False
			i += 1
		
		self.findDFS(0, visited)
		i = 1
		while (i < self.vertices) :
			if (visited[i] == False) :
				#  When [i] vertices are not visit
				return False
			
			i += 1
		
		return True
	
	def printGraph(self) :
		print("\n Graph Adjacency List ", end = "")
		i = 0
		while (i < self.vertices) :
			print(" \n [", i ,"] :", end = "")
			j = 0
			#  iterate edges of i node
			while (j < len(self.adgeList[i])) :
				print("  ", self.adgeList[i][j], end = "")
				j += 1
			
			i += 1
		
	
	def reverseDeleteMST(self) :
		result = 0
		#  Get first higher edge
		point = self.edges
		print("\n\nConnected node by Edges in MST")
		#  iterates the edge from high to low order
		while (point != None) :
			#  Remove the current weight edge of node from u to v and v to u
			self.adgeList[point.u].remove(point.v)
			self.adgeList[point.v].remove(point.u)
			if (self.isConnected() == False) :
				#  When delete edge are create problems (). 
				#  Then they are add back into graph
				self.adgeList[point.u].append(point.v)
				self.adgeList[point.v].append(point.u)
				#  Update weight    
				result += point.weight
				#  Display edge
				print(" (", point.u ,", ", point.v ,") ")
			
			#  Visit next smaller weight edge
			point = point.next
		
		print("Calculated total weight of MST is ", result)
	

def main() :
	g = Graph(8)
	g.addEdge(0, 1, 5)
	g.addEdge(0, 3, 3)
	g.addEdge(1, 2, 3)
	g.addEdge(1, 6, 7)
	g.addEdge(1, 7, 9)
	g.addEdge(2, 5, 9)
	g.addEdge(2, 7, 4)
	g.addEdge(3, 4, 11)
	g.addEdge(3, 7, 8)
	g.addEdge(4, 5, 8)
	g.addEdge(4, 6, 14)
	g.addEdge(4, 7, 10)
	g.addEdge(5, 6, 11)
	#  Display graph element
	g.printGraph()
	#  Find MST
	g.reverseDeleteMST()

if __name__ == "__main__": main()

input

 Graph Adjacency List
 [ 0 ] :   1   3
 [ 1 ] :   0   2   6   7
 [ 2 ] :   1   5   7
 [ 3 ] :   0   4   7
 [ 4 ] :   3   5   6   7
 [ 5 ] :   2   4   6
 [ 6 ] :   1   4   5
 [ 7 ] :   1   2   3   4

Connected node by Edges in MST
 ( 2 ,  5 )
 ( 4 ,  5 )
 ( 1 ,  6 )
 ( 0 ,  1 )
 ( 2 ,  7 )
 ( 1 ,  2 )
 ( 0 ,  3 )
Calculated total weight of MST is  39
#    Ruby Program
#    Reverse delete algorithm for minimum spanning tree
class Edge 
	# Define the accessor and reader of class Edge
	attr_reader :weight, :u, :v, :next
	attr_accessor :weight, :u, :v, :next
	#  edge weight or cost  
	def initialize(weight, u, v) 
		self.weight = weight
		self.u = u
		self.v = v
		self.next = nil
	end

end

class Graph 
	# Define the accessor and reader of class Graph
	attr_reader :vertices, :adgeList, :edges, :edgeCount
	attr_accessor :vertices, :adgeList, :edges, :edgeCount
	def initialize(vertices) 
		self.vertices = vertices
		self.adgeList = []
		self.edges = nil
		self.edgeCount = 0
		i = 0
		while (i < self.vertices) 
			self.adgeList.push([])
			i += 1
		end

	end

	def addEdge(u, v, w) 
		if (u < 0 || u >= self.vertices || v < 0 || v >= self.vertices) 
			return
		end

		#  add node edge
		self.adgeList[u].push(v)
		self.adgeList[v].push(u)
		#  Collect descending order sorted edges
		#  Create new edge
		e = Edge.new(w, u, v)
		#  Add edge in decreasing order
		if (self.edges == nil) 
			#  First edge
			self.edges = e
		elsif (self.edges.weight <= e.weight) 
			#  Add edges in front
			e.next = self.edges
			self.edges = e
		else
 
			temp = self.edges
			#  Find position to add new edge
			while (temp.next != nil && temp.next.weight > e.weight) 
				temp = temp.next
			end

			e.next = temp.next
			temp.next = e
		end

		self.edgeCount = self.edgeCount + 1
	end

	#  Perform DFS
	def findDFS(v, visited) 
		#  Indicates the current vertex is visited
		visited[v] = true
		#  iterate edges of v node
		for i in self.adgeList[v]
			if (visited[i] == false) 
				self.findDFS(i, visited)
			end
			i += 1
		end

	end

	#  Check that graph start vertices are reach to all other vertices or not
	def isConnected() 
		visited = Array.new(self.vertices) {false}
		i = 0
		#  Set the initial visited vertices
		while (i < self.vertices) 
			visited[i] = false
			i += 1
		end

		self.findDFS(0, visited)
		i = 1
		while (i < self.vertices) 
			if (visited[i] == false) 
				#  When [i] vertices are not visit
				return false
			end

			i += 1
		end

		return true
	end

	def printGraph() 
		print("\n Graph Adjacency List ")
		i = 0
		while (i < self.vertices) 
			print(" \n [", i ,"] :")
			j = 0
			#  iterate edges of i node
			while (j < self.adgeList[i].length) 
				print("  ", self.adgeList[i][j])
				j += 1
			end

			i += 1
		end

	end

	def reverseDeleteMST() 
		result = 0
		#  Get first higher edge
		point = self.edges
		print("\n\nConnected node by Edges in MST", "\n")
		#  iterates the edge from high to low order
		while (point != nil)
          
			#  Remove the current weight edge of node from u to v and v to u
			self.adgeList[point.u] -= [point.v]
			self.adgeList[point.v] -= [point.u]
			
			if (self.isConnected() == false) 
				#  When delete edge are create problems (). 
				#  Then they are add back into graph
				self.adgeList[point.u].push(point.v)
				self.adgeList[point.v].push(point.u)
				#  Update weight    
				result += point.weight
				#  Display edge
				print(" (", point.u ,", ", point.v ,") \n")
			end

			#  Visit next smaller weight edge
			point = point.next
		end

		print("Calculated total weight of MST is ", result, "\n")
	end

end

def main() 
	g = Graph.new(8)
	g.addEdge(0, 1, 5)
	g.addEdge(0, 3, 3)
	g.addEdge(1, 2, 3)
	g.addEdge(1, 6, 7)
	g.addEdge(1, 7, 9)
	g.addEdge(2, 5, 9)
	g.addEdge(2, 7, 4)
	g.addEdge(3, 4, 11)
	g.addEdge(3, 7, 8)
	g.addEdge(4, 5, 8)
	g.addEdge(4, 6, 14)
	g.addEdge(4, 7, 10)
	g.addEdge(5, 6, 11)
	#  Display graph element
	g.printGraph()
	#  Find MST
	g.reverseDeleteMST()
end

main()

input

 Graph Adjacency List  
 [0] :  1  3 
 [1] :  0  2  6  7 
 [2] :  1  5  7 
 [3] :  0  4  7 
 [4] :  3  5  6  7 
 [5] :  2  4  6 
 [6] :  1  4  5 
 [7] :  1  2  3  4

Connected node by Edges in MST
 (2, 5) 
 (4, 5) 
 (1, 6) 
 (0, 1) 
 (2, 7) 
 (1, 2) 
 (0, 3) 
Calculated total weight of MST is 39
import scala.collection.mutable._;
/*
    Scala Program
    Reverse delete algorithm for minimum spanning tree
*/
class Edge(
	// edge weight or cost  
	var weight: Int,
		var u: Int,
			var v: Int,
				var next: Edge)
{
	def this(weight: Int, u: Int, v: Int)
	{
		this(weight, u,v,null);
	}
}
class Graph(var vertices: Int,
	var adgeList: ArrayBuffer[ArrayBuffer[Int]],
		var edges: Edge,
			var edgeCount: Int)
{
	def this(vertices: Int)
	{
		this(vertices,new ArrayBuffer[ArrayBuffer[Int]](vertices), null,0);
		var i: Int = 0;
		while (i < this.vertices)
		{
			this.adgeList += new ArrayBuffer[Int]();
			i += 1;
		}
	}
	def addEdge(u: Int, v: Int, w: Int): Unit = {
		if (u < 0 || u >= this.vertices || v < 0 || v >= this.vertices)
		{
			return;
		}
		// add node edge
		adgeList(u) += v;
		adgeList(v) += u;
		// Collect descending order sorted edges
		// Create new edge
		var e: Edge = new Edge(w, u, v);
		// Add edge in decreasing order
		if (this.edges == null)
		{
			// First edge
			this.edges = e;
		}
		else if (this.edges.weight <= e.weight)
		{
			// Add edges in front
			e.next = this.edges;
			this.edges = e;
		}
		else
		{
			var temp: Edge = this.edges;
			// Find position to add new edge
			while (temp.next != null && temp.next.weight > e.weight)
			{
				temp = temp.next;
			}
			e.next = temp.next;
			temp.next = e;
		}
		this.edgeCount = this.edgeCount + 1;
	}
	// Perform DFS
	def findDFS(v: Int, visited: Array[Boolean]): Unit = {
		// Indicates the current vertex is visited
		visited(v) = true;
		var i: Int = 0;
		// iterate edges of v node
		while (i < this.adgeList(v).size)
		{
			if (visited(this.adgeList(v)(i)) == false)
			{
				findDFS(this.adgeList(v)(i), visited);
			}
			i += 1;
		}
	}
	// Check that graph start vertices are reach to all other vertices or not
	def isConnected(): Boolean = {
		var visited: Array[Boolean] = Array.fill[Boolean](this.vertices)(false);
		this.findDFS(0, visited);
		var i: Int = 1;
		while (i < this.vertices)
		{
			if (visited(i) == false)
			{
				// When [i] vertices are not visit
				return false;
			}
			i += 1;
		}
		return true;
	}
	def printGraph(): Unit = {
		print("\n Graph Adjacency List ");
		var i: Int = 0;
		while (i < this.vertices)
		{
			print(" \n [" + i + "] :");
			var j: Int = 0;
			// iterate edges of i node
			while (j < this.adgeList(i).size)
			{
				print("  " + this.adgeList(i)(j));
				j += 1;
			}
			i += 1;
		}
	}
	def reverseDeleteMST(): Unit = {
		var result: Int = 0;
		// Get first higher edge
		var point: Edge = this.edges;
		println("\n\nConnected node by Edges in MST");
		// iterates the edge from high to low order
		while (point != null)
		{
			// Remove the current weight edge of node from u to v and v to u
			adgeList(point.u) -= point.v;
			adgeList(point.v) -= point.u;
			if (isConnected() == false)
			{
				// When delete edge are create problems (). 
				// Then they are add back into graph
				adgeList(point.u) += point.v;
				adgeList(point.v) += point.u;
				// Update weight    
				result += point.weight;
				// Display edge
				print(" (" + point.u + ", " + point.v + ") \n");
			}
			// Visit next smaller weight edge
			point = point.next;
		}
		println("Calculated total weight of MST is " + result);
	}
}
object Main
{
	def main(args: Array[String]): Unit = {
		var g: Graph = new Graph(8);
		g.addEdge(0, 1, 5);
		g.addEdge(0, 3, 3);
		g.addEdge(1, 2, 3);
		g.addEdge(1, 6, 7);
		g.addEdge(1, 7, 9);
		g.addEdge(2, 5, 9);
		g.addEdge(2, 7, 4);
		g.addEdge(3, 4, 11);
		g.addEdge(3, 7, 8);
		g.addEdge(4, 5, 8);
		g.addEdge(4, 6, 14);
		g.addEdge(4, 7, 10);
		g.addEdge(5, 6, 11);
		// Display graph element
		g.printGraph();
		// Find MST
		g.reverseDeleteMST();
	}
}

input

 Graph Adjacency List
 [0] :  1  3
 [1] :  0  2  6  7
 [2] :  1  5  7
 [3] :  0  4  7
 [4] :  3  5  6  7
 [5] :  2  4  6
 [6] :  1  4  5
 [7] :  1  2  3  4

Connected node by Edges in MST
 (2, 5)
 (4, 5)
 (1, 6)
 (0, 1)
 (2, 7)
 (1, 2)
 (0, 3)
Calculated total weight of MST is 39
import Foundation;
/*
    Swift 4 Program
    Reverse delete algorithm for minimum spanning tree
*/
class Edge
{
	// edge weight or cost  
	var weight: Int;
	var u: Int;
	var v: Int;
	var next: Edge? ;
	init(_ weight: Int, _ u: Int, _ v: Int)
	{
		self.weight = weight;
		self.u = u;
		self.v = v;
		self.next = nil;
	}
}
class Graph
{
	var vertices: Int;
	var adgeList: [
		[Int]
	];
	var edges: Edge? ;
	var edgeCount: Int;
	init(_ vertices: Int)
	{
		self.vertices = vertices;
		self.adgeList = [[Int]]();
		self.edges = nil;
		self.edgeCount = 0;
		var i = 0;
		while (i < self.vertices)
		{
			self.adgeList.append([Int]());
			i += 1;
		}
	}
	func addEdge(_ u: Int, _ v: Int, _ w: Int)
	{
		if (u < 0 || u >= self.vertices || v < 0 || v >= self.vertices)
		{
			return;
		}
		// add node edge
		self.adgeList[u].append(v);
		self.adgeList[v].append(u);
		// Collect descending order sorted edges
		// Create new edge
		let e = Edge(w, u, v);
		// Add edge in decreasing order
		if (self.edges == nil)
		{
			// First edge
			self.edges = e;
		}
		else if (self.edges!.weight <= e.weight)
		{
			// Add edges in front
			e.next = self.edges;
			self.edges = e;
		}
		else
		{
			var temp = self.edges;
			// Find position to add new edge
			while (temp!.next  != nil && temp!.next!.weight > e.weight)
			{
				temp = temp!.next;
			}
			e.next = temp!.next;
			temp!.next = e;
		}
		self.edgeCount = self.edgeCount + 1;
	}
	// Perform DFS
	func findDFS(_ v: Int, _ visited: inout[Bool])
	{
		// Indicates the current vertex is visited
		visited[v] = true;
		var i = 0;
		// iterate edges of v node
		while (i < self.adgeList[v].count)
		{
			if (visited[self.adgeList[v][i]] == false)
			{
				self.findDFS(self.adgeList[v][i], &visited);
			}
			i += 1;
		}
	}
	// Check that graph start vertices are reach to all other vertices or not
	func isConnected() -> Bool
	{
		var visited = Array(repeating: false, count: self.vertices);

		self.findDFS(0, &visited);
		var i = 1;
		while (i < self.vertices)
		{
			if (visited[i] == false)
			{
				// When [i] vertices are not visit
				return false;
			}
			i += 1;
		}
		return true;
	}
	func printGraph()
	{
		print("\n Graph Adjacency List ", terminator: "");
		var i = 0;
		while (i < self.vertices)
		{
			print(" \n [", i ,"] :", terminator: "");
			var j = 0;
			// iterate edges of i node
			while (j < self.adgeList[i].count)
			{
				print("  ", self.adgeList[i][j], terminator: "");
				j += 1;
			}
			i += 1;
		}
	}
	func reverseDeleteMST()
	{
		var result = 0;
		// Get first higher edge
		var point = self.edges;
		print("\n\nConnected node by Edges in MST");
		// iterates the edge from high to low order
		while (point  != nil)
		{
			// Remove the current weight edge of node from u to v and v to u
          	if let k1 = self.adgeList[point!.u].index(of:point!.v) {
                self.adgeList[point!.u].remove(at: k1)
            }
          	if let k2 = self.adgeList[point!.v].index(of:point!.u) {
                self.adgeList[point!.v].remove(at: k2)
            }
          
			if (self.isConnected() == false)
			{
				// When delete edge are create problems (). 
				// Then they are add back into graph
				self.adgeList[point!.u].append(point!.v);
				self.adgeList[point!.v].append(point!.u);
				// Update weight    
				result += point!.weight;
				// Display edge
				print(" (", point!.u ,", ", point!.v ,") ");
			}
			// Visit next smaller weight edge
			point = point!.next;
		}
		print("Calculated total weight of MST is ", result);
	}
}
func main()
{
	let g = Graph(8);
	g.addEdge(0, 1, 5);
	g.addEdge(0, 3, 3);
	g.addEdge(1, 2, 3);
	g.addEdge(1, 6, 7);
	g.addEdge(1, 7, 9);
	g.addEdge(2, 5, 9);
	g.addEdge(2, 7, 4);
	g.addEdge(3, 4, 11);
	g.addEdge(3, 7, 8);
	g.addEdge(4, 5, 8);
	g.addEdge(4, 6, 14);
	g.addEdge(4, 7, 10);
	g.addEdge(5, 6, 11);
	// Display graph element
	g.printGraph();
	// Find MST
	g.reverseDeleteMST();
}
main();

input

 Graph Adjacency List
 [ 0 ] :   1   3
 [ 1 ] :   0   2   6   7
 [ 2 ] :   1   5   7
 [ 3 ] :   0   4   7
 [ 4 ] :   3   5   6   7
 [ 5 ] :   2   4   6
 [ 6 ] :   1   4   5
 [ 7 ] :   1   2   3   4

Connected node by Edges in MST
 ( 2 ,  5 )
 ( 4 ,  5 )
 ( 1 ,  6 )
 ( 0 ,  1 )
 ( 2 ,  7 )
 ( 1 ,  2 )
 ( 0 ,  3 )
Calculated total weight of MST is  39
/*
    Kotlin Program
    Reverse delete algorithm for minimum spanning tree
*/
class Edge
{
	// edge weight or cost  
	var weight: Int;
	var u: Int;
	var v: Int;
	var next: Edge ? ;
	constructor(weight: Int, u: Int, v: Int)
	{
		this.weight = weight;
		this.u = u;
		this.v = v;
		this.next = null;
	}
}
class Graph
{
	var vertices: Int;
	var adgeList: MutableList <MutableList<Int>> ;
	var edges: Edge ? ;
	var edgeCount: Int;
	constructor(vertices: Int)
	{
		this.vertices = vertices;
		this.adgeList = mutableListOf<MutableList<Int>>();
		this.edges = null;
		this.edgeCount = 0;
		var i: Int = 0;
		while (i < this.vertices)
		{
			this.adgeList.add(mutableListOf<Int>());
			i += 1;
		}
	}
	fun addEdge(u: Int, v: Int, w: Int): Unit
	{
		if (u < 0 || u >= this.vertices || v < 0 || v >= this.vertices)
		{
			return;
		}
		// add node edge
		this.adgeList[u].add(v);
		this.adgeList[v].add(u);
		// Collect descending order sorted edges
		// Create new edge
		val e: Edge = Edge(w, u, v);
		// Add edge in decreasing order
		if (this.edges == null)
		{
			// First edge
			this.edges = e;
		}
		else if (this.edges!!.weight <= e.weight)
		{
			// Add edges in front
			e.next = this.edges;
			this.edges = e;
		}
		else
		{
			var temp: Edge? = this.edges;
			// Find position to add new edge
			while ( temp?.next != null 
              && temp.next!!.weight > e.weight)
			{
				temp = temp.next;
			}
			e.next = temp?.next;
			temp?.next = e;
		}
		this.edgeCount = this.edgeCount + 1;
	}
	// Perform DFS
	fun findDFS(v: Int, visited: Array < Boolean > ): Unit
	{
		// Indicates the current vertex is visited
		visited[v] = true;
		var i: Int = 0;
		// iterate edges of v node
		while (i < this.adgeList[v].size)
		{
			if (visited[this.adgeList[v][i]] == false)
			{
				this.findDFS(this.adgeList[v][i], visited);
			}
			i += 1;
		}
	}
	// Check that graph start vertices are reach to all other vertices or not
	fun isConnected(): Boolean
	{
		val visited: Array < Boolean > = Array(this.vertices)
		{
			false
		};
		this.findDFS(0, visited);
		var i: Int = 1;
		while (i < this.vertices)
		{
			if (visited[i] == false)
			{
				// When [i] vertices are not visit
				return false;
			}
			i += 1;
		}
		return true;
	}
	fun printGraph(): Unit
	{
		print("\n Graph Adjacency List ");
		var i: Int = 0;
		while (i < this.vertices)
		{
			print(" \n [" + i + "] :");
			var j: Int = 0;
			// iterate edges of i node
			while (j < this.adgeList[i].size)
			{
				print("  " + this.adgeList[i][j]);
				j += 1;
			}
			i += 1;
		}
	}
	fun reverseDeleteMST(): Unit
	{
		var result: Int = 0;
		// Get first higher edge
		var point: Edge ? = this.edges;
		println("\n\nConnected node by Edges in MST");
		// iterates the edge from high to low order
		while (point != null)
		{
			// Remove the current weight edge of node from u to v and v to u
			this.adgeList[point.u].remove(point.v);
			this.adgeList[point.v].remove(point.u);
			if (this.isConnected() == false)
			{
				// When delete edge are create problems (). 
				// Then they are add back into graph
				this.adgeList[point.u].add(point.v);
				this.adgeList[point.v].add(point.u);
				// Update weight    
				result += point.weight;
				// Display edge
				print(" (" + point.u + ", " + point.v + ") \n");
			}
			// Visit next smaller weight edge
			point = point.next;
		}
		println("Calculated total weight of MST is " + result);
	}
}
fun main(args: Array < String > ): Unit
{
	val g: Graph = Graph(8);
	g.addEdge(0, 1, 5);
	g.addEdge(0, 3, 3);
	g.addEdge(1, 2, 3);
	g.addEdge(1, 6, 7);
	g.addEdge(1, 7, 9);
	g.addEdge(2, 5, 9);
	g.addEdge(2, 7, 4);
	g.addEdge(3, 4, 11);
	g.addEdge(3, 7, 8);
	g.addEdge(4, 5, 8);
	g.addEdge(4, 6, 14);
	g.addEdge(4, 7, 10);
	g.addEdge(5, 6, 11);
	// Display graph element
	g.printGraph();
	// Find MST
	g.reverseDeleteMST();
}

input

 Graph Adjacency List
 [0] :  1  3
 [1] :  0  2  6  7
 [2] :  1  5  7
 [3] :  0  4  7
 [4] :  3  5  6  7
 [5] :  2  4  6
 [6] :  1  4  5
 [7] :  1  2  3  4

Connected node by Edges in MST
 (2, 5)
 (4, 5)
 (1, 6)
 (0, 1)
 (2, 7)
 (1, 2)
 (0, 3)
Calculated total weight of MST is 39

Output Explanation

The output displays the adjacency list of the graph along with the edges that are part of the minimum spanning tree. Each edge (u, v) indicates that there is a connection between vertex u and vertex v in the minimum spanning tree. The total weight of the minimum spanning tree is also calculated and printed.

Time Complexity

The time complexity of the reverse delete algorithm mainly depends on the sorting of the edges, which takes O(E log E) time. Additionally, for each edge, the algorithm checks connectivity using the Depth-First Search (DFS) method, which has a time complexity of O(V + E). Therefore, the overall time complexity is dominated by O(E log E), where E is the number of edges.

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