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Maximum sum of values of nodes among all connected components of an undirected graph
  • Difficulty Level : Medium
  • Last Updated : 18 Sep, 2020
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Given an undirected graph with V vertices and E edges. Every node has been assigned a given value. The task is to find the connected chain with the maximum sum of of values among all the connected components in the graph. 
Examples:

Input: V = 7, E = 4 
Values = {10, 25, 5, 15, 5, 20, 0} 
 

Output : Max Sum value = 35 
Explanation: 
Component {1, 2} – Value {10, 25}: sumValue = 10 + 25 = 35 
Component {3, 4, 5} – Value {5, 15, 5}: sumValue = 5 + 15 + 5 = 25 
Component {6, 7} – Value {20, 0}: sumValue = 20 + 0 = 20 
Max Sum value chain is {1, 2} with values {10, 25}, hence 35 is answer. 

Input: V = 10, E = 6 
Values = {5, 10, 15, 20, 25, 30, 35, 40, 45, 50}



Output : Max Sum value = 105

Approach: The idea is to use the Depth First Search traversal method to keep a track of all the connected components. A temporary variable is used to sum up all the values of the individual values of the connected chains. At each traversal of a connected component, the heaviest value till now is compared with the current value and updated accordingly. After all connected components have been traversed, the maximum among all will the answer. 

Below is the implementation of the above approach:

C++




// C++ program to find Maximum sum of values
// of nodes among all connected
// components of an undirected graph
#include <bits/stdc++.h>
using namespace std;
  
// Function to implement DFS
void depthFirst(int v, vector<int> graph[],
                vector<bool>& visited,
                int& sum,
                vector<int> values)
{
    // Marking the visited vertex as true
    visited[v] = true;
  
    // Updating the value of connection
    sum += values[v - 1];
  
    // Traverse for all adjacent nodes
    for (auto i : graph[v]) {
  
        if (visited[i] == false) {
  
            // Recursive call to the DFS algorithm
            depthFirst(i, graph, visited,
                       sum, values);
        }
    }
}
  
void maximumSumOfValues(vector<int> graph[],
                        int vertices, vector<int> values)
{
    // Initializing boolean array to mark visited vertices
    vector<bool> visited(values.size() + 1, false);
  
    // maxChain stores the maximum chain size
    int maxValueSum = INT_MIN;
  
    // Following loop invokes DFS algorithm
    for (int i = 1; i <= vertices; i++) {
        if (visited[i] == false) {
  
            // Variable to hold temporary values
            int sum = 0;
  
            // DFS algorithm
            depthFirst(i, graph, visited,
                       sum, values);
  
            // Conditional to update max value
            if (sum > maxValueSum) {
                maxValueSum = sum;
            }
        }
    }
  
    // Printing the heaviest chain value
    cout << "Max Sum value = ";
    cout << maxValueSum << "\n";
}
  
// Driver function to test above function
int main()
{
    // Initializing graph in the form of adjacency list
    vector<int> graph[1001];
  
    // Defining the number of edges and vertices
    int E = 4, V = 7;
  
    // Assigning the values for each
    // vertex of the undirected graph
    vector<int> values;
    values.push_back(10);
    values.push_back(25);
    values.push_back(5);
    values.push_back(15);
    values.push_back(5);
    values.push_back(20);
    values.push_back(0);
  
    // Constructing the undirected graph
    graph[1].push_back(2);
    graph[2].push_back(1);
    graph[3].push_back(4);
    graph[4].push_back(3);
    graph[3].push_back(5);
    graph[5].push_back(3);
    graph[6].push_back(7);
    graph[7].push_back(6);
  
    maximumSumOfValues(graph, V, values);
    return 0;
}

Java




// Java program to find Maximum sum of
// values of nodes among all connected
// components of an undirected graph
import java.util.*;
  
class GFG{
      
static int sum;
  
// Function to implement DFS
static void depthFirst(int v,
                       Vector<Integer> graph[],
                       boolean []visited,
                       Vector<Integer> values)
{
      
    // Marking the visited vertex as true
    visited[v] = true;
  
    // Updating the value of connection
    sum += values.get(v - 1);
  
    // Traverse for all adjacent nodes
    for(int i : graph[v]) 
    {
        if (visited[i] == false)
        {
              
            // Recursive call to the DFS algorithm
            depthFirst(i, graph, visited, values);
        }
    }
}
  
static void maximumSumOfValues(Vector<Integer> graph[],
                               int vertices, 
                               Vector<Integer> values)
{
      
    // Initializing boolean array to
    // mark visited vertices
    boolean []visited = new boolean[values.size() + 1];
  
    // maxChain stores the maximum chain size
    int maxValueSum = Integer.MIN_VALUE;
  
    // Following loop invokes DFS algorithm
    for(int i = 1; i <= vertices; i++) 
    {
        if (visited[i] == false)
        {
              
            // Variable to hold temporary values
            sum = 0;
  
            // DFS algorithm
            depthFirst(i, graph, visited, values);
  
            // Conditional to update max value
            if (sum > maxValueSum)
            {
                maxValueSum = sum;
            }
        }
    }
      
    // Printing the heaviest chain value
    System.out.print("Max Sum value = ");
    System.out.print(maxValueSum + "\n");
}
  
// Driver code
public static void main(String[] args)
{
      
    // Initializing graph in the form
    // of adjacency list
    @SuppressWarnings("unchecked")
    Vector<Integer> []graph = new Vector[1001];
      
    for(int i = 0; i < graph.length; i++)
        graph[i] = new Vector<Integer>();
          
    // Defining the number of edges and vertices
    int E = 4, V = 7;
  
    // Assigning the values for each
    // vertex of the undirected graph
    Vector<Integer> values = new Vector<Integer>();
    values.add(10);
    values.add(25);
    values.add(5);
    values.add(15);
    values.add(5);
    values.add(20);
    values.add(0);
  
    // Constructing the undirected graph
    graph[1].add(2);
    graph[2].add(1);
    graph[3].add(4);
    graph[4].add(3);
    graph[3].add(5);
    graph[5].add(3);
    graph[6].add(7);
    graph[7].add(6);
  
    maximumSumOfValues(graph, V, values);
}
}
  
// This code is contributed by Rajput-Ji

Python3




# Python3 program to find Maximum sum
# of values of nodes among all connected
# components of an undirected graph
import sys
  
graph = [[] for i in range(1001)]
visited = [False] * (1001 + 1)
sum = 0
  
# Function to implement DFS
def depthFirst(v, values):
      
    global sum
      
    # Marking the visited vertex as true
    visited[v] = True
  
    # Updating the value of connection
    sum += values[v - 1]
  
    # Traverse for all adjacent nodes
    for i in graph[v]:
        if (visited[i] == False):
  
            # Recursive call to the 
            # DFS algorithm
            depthFirst(i, values)
  
def maximumSumOfValues(vertices,values):
      
    global sum
      
    # Initializing boolean array to
    # mark visited vertices
  
    # maxChain stores the maximum chain size
    maxValueSum = -sys.maxsize - 1
  
    # Following loop invokes DFS algorithm
    for i in range(1, vertices + 1):
        if (visited[i] == False):
  
            # Variable to hold temporary values
            # sum = 0
  
            # DFS algorithm
            depthFirst(i, values)
  
            # Conditional to update max value
            if (sum > maxValueSum):
                maxValueSum = sum
                  
            sum = 0
              
    # Printing the heaviest chain value
    print("Max Sum value = ", end = "")
    print(maxValueSum)
  
# Driver code
if __name__ == '__main__':
      
    # Initializing graph in the
    # form of adjacency list
  
    # Defining the number of 
    # edges and vertices
    E = 4
    V = 7
  
    # Assigning the values for each
    # vertex of the undirected graph
    values = []
    values.append(10)
    values.append(25)
    values.append(5)
    values.append(15)
    values.append(5)
    values.append(20)
    values.append(0)
  
    # Constructing the undirected graph
    graph[1].append(2)
    graph[2].append(1)
    graph[3].append(4)
    graph[4].append(3)
    graph[3].append(5)
    graph[5].append(3)
    graph[6].append(7)
    graph[7].append(6)
  
    maximumSumOfValues(V, values)
  
# This code is contributed by mohit kumar 29

C#




// C# program to find Maximum sum of
// values of nodes among all connected
// components of an undirected graph
using System;
using System.Collections.Generic;
  
class GFG{
      
static int sum;
  
// Function to implement DFS
static void depthFirst(int v,
                       List<int> []graph,
                       bool []visited,
                       List<int> values)
{
      
    // Marking the visited vertex as true
    visited[v] = true;
  
    // Updating the value of connection
    sum += values[v - 1];
  
    // Traverse for all adjacent nodes
    foreach(int i in graph[v]) 
    {
        if (visited[i] == false)
        {
              
            // Recursive call to the DFS algorithm
            depthFirst(i, graph, visited, values);
        }
    }
}
  
static void maximumSumOfValues(List<int> []graph,
                               int vertices, 
                               List<int> values)
{
      
    // Initializing bool array to
    // mark visited vertices
    bool []visited = new bool[values.Count + 1];
  
    // maxChain stores the maximum chain size
    int maxValueSum = int.MinValue;
  
    // Following loop invokes DFS algorithm
    for(int i = 1; i <= vertices; i++) 
    {
        if (visited[i] == false)
        {
              
            // Variable to hold temporary values
            sum = 0;
  
            // DFS algorithm
            depthFirst(i, graph, visited, values);
  
            // Conditional to update max value
            if (sum > maxValueSum)
            {
                maxValueSum = sum;
            }
        }
    }
      
    // Printing the heaviest chain value
    Console.Write("Max Sum value = ");
    Console.Write(maxValueSum + "\n");
}
  
// Driver code
public static void Main(String[] args)
{
      
    // Initializing graph in the form
    // of adjacency list
    List<int> []graph = new List<int>[1001];
      
    for(int i = 0; i < graph.Length; i++)
        graph[i] = new List<int>();
          
    // Defining the number of edges and vertices
    int V = 7;
  
    // Assigning the values for each
    // vertex of the undirected graph
    List<int> values = new List<int>();
      
    values.Add(10);
    values.Add(25);
    values.Add(5);
    values.Add(15);
    values.Add(5);
    values.Add(20);
    values.Add(0);
  
    // Constructing the undirected graph
    graph[1].Add(2);
    graph[2].Add(1);
    graph[3].Add(4);
    graph[4].Add(3);
    graph[3].Add(5);
    graph[5].Add(3);
    graph[6].Add(7);
    graph[7].Add(6);
  
    maximumSumOfValues(graph, V, values);
}
}
  
// This code is contributed by Amit Katiyar
Output: 
Max Sum value = 35

Time Complexity: O(E + V)
 

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