Print nodes having maximum and minimum degrees

• Difficulty Level : Expert
• Last Updated : 18 Aug, 2021

Given an undirected graph having N nodes, the task is to print the nodes having minimum and maximum degree.
Examples:

Input:
1-----2
|     |
3-----4
Output:
Nodes with maximum degree : 1 2 3 4
Nodes with minimum degree : 1 2 3 4
Every node has a degree of 2.

Input:
1
/ \
2   3
/
4
Output:
Nodes with maximum degree : 1 2
Nodes with minimum degree : 3 4

Approach: For an undirected graph, the degree of a node is the number of edges incident to it, so the degree of each node can be calculated by counting its frequency in the list of edges. Hence the approach is to use a map to calculate the frequency of every vertex from the edge list and use the map to find the nodes having maximum and minimum degrees.
Below is the implementation of the above approach:

C++

 // C++ implementation of the approach#include using namespace std; // Function to print the nodes having// maximum and minimum degreevoid minMax(int edges[], int len, int n){     // Map to store the degrees of every node    map m;     for (int i = 0; i < len; i++) {         // Storing the degree for each node        m[edges[i]]++;        m[edges[i]]++;    }     // maxi and mini variables to store    // the maximum and minimum degree    int maxi = 0;    int mini = n;     for (int i = 1; i <= n; i++) {        maxi = max(maxi, m[i]);        mini = min(mini, m[i]);    }     // Printing all the nodes with maximum degree    cout << "Nodes with maximum degree : ";    for (int i = 1; i <= n; i++) {        if (m[i] == maxi)            cout << i << " ";    }    cout << endl;     // Printing all the nodes with minimum degree    cout << "Nodes with minimum degree : ";    for (int i = 1; i <= n; i++) {        if (m[i] == mini)            cout << i << " ";    }} // Driver codeint main(){     // Count of nodes and edges    int n = 4, m = 6;     // The edge list    int edges[] = { { 1, 2 },                       { 1, 3 },                       { 1, 4 },                       { 2, 3 },                       { 2, 4 },                       { 3, 4 } };     minMax(edges, m, 4);     return 0;}

Java

 // Java implementation of the approachimport java.util.*; class GFG{ // Function to print the nodes having// maximum and minimum degreestatic void minMax(int edges[][], int len, int n){     // Map to store the degrees of every node    HashMap m = new HashMap();     for (int i = 0; i < len; i++)    {         // Storing the degree for each node        if(m.containsKey(edges[i]))        {            m.put(edges[i], m.get(edges[i]) + 1);        }        else        {            m.put(edges[i], 1);        }        if(m.containsKey(edges[i]))        {            m.put(edges[i], m.get(edges[i]) + 1);        }        else        {            m.put(edges[i], 1);        }    }     // maxi and mini variables to store    // the maximum and minimum degree    int maxi = 0;    int mini = n;     for (int i = 1; i <= n; i++)    {        maxi = Math.max(maxi, m.get(i));        mini = Math.min(mini, m.get(i));    }     // Printing all the nodes with maximum degree    System.out.print("Nodes with maximum degree : ");    for (int i = 1; i <= n; i++)    {        if (m.get(i) == maxi)            System.out.print(i + " ");    }    System.out.println();     // Printing all the nodes with minimum degree    System.out.print("Nodes with minimum degree : ");    for (int i = 1; i <= n; i++)    {        if (m.get(i) == mini)            System.out.print(i + " ");    }} // Driver codepublic static void main(String[] args){    // Count of nodes and edges    int n = 4, m = 6;     // The edge list    int edges[][] = {{ 1, 2 }, { 1, 3 },                     { 1, 4 }, { 2, 3 },                     { 2, 4 }, { 3, 4 }};     minMax(edges, m, 4);}} // This code is contributed by PrinciRaj1992

Python3

 # Python3 implementation of the approach # Function to print the nodes having# maximum and minimum degreedef minMax(edges, leng, n) :     # Map to store the degrees of every node    m = {};         for i in range(leng) :        m[edges[i]] = 0;        m[edges[i]] = 0;             for i in range(leng) :                 # Storing the degree for each node        m[edges[i]] += 1;        m[edges[i]] += 1;     # maxi and mini variables to store    # the maximum and minimum degree    maxi = 0;    mini = n;     for i in range(1, n + 1) :        maxi = max(maxi, m[i]);        mini = min(mini, m[i]);     # Printing all the nodes    # with maximum degree    print("Nodes with maximum degree : ",                                end = "")         for i in range(1, n + 1) :        if (m[i] == maxi) :            print(i, end = " ");     print()     # Printing all the nodes    # with minimum degree    print("Nodes with minimum degree : ",                                end = "")         for i in range(1, n + 1) :        if (m[i] == mini) :            print(i, end = " "); # Driver codeif __name__ == "__main__" :     # Count of nodes and edges    n = 4; m = 6;     # The edge list    edges = [[ 1, 2 ], [ 1, 3 ],             [ 1, 4 ], [ 2, 3 ],             [ 2, 4 ], [ 3, 4 ]];     minMax(edges, m, 4); # This code is contributed by AnkitRai01

C#

 // C# implementation of the approachusing System;using System.Collections.Generic; class GFG{ // Function to print the nodes having// maximum and minimum degreestatic void minMax(int [,]edges, int len, int n){     // Map to store the degrees of every node    Dictionary m = new Dictionary();     for (int i = 0; i < len; i++)    {         // Storing the degree for each node        if(m.ContainsKey(edges[i, 0]))        {            m[edges[i, 0]] = m[edges[i, 0]] + 1;        }        else        {            m.Add(edges[i, 0], 1);        }        if(m.ContainsKey(edges[i, 1]))        {            m[edges[i, 1]] = m[edges[i, 1]] + 1;        }        else        {            m.Add(edges[i, 1], 1);        }    }     // maxi and mini variables to store    // the maximum and minimum degree    int maxi = 0;    int mini = n;     for (int i = 1; i <= n; i++)    {        maxi = Math.Max(maxi, m[i]);        mini = Math.Min(mini, m[i]);    }     // Printing all the nodes with maximum degree    Console.Write("Nodes with maximum degree : ");    for (int i = 1; i <= n; i++)    {        if (m[i] == maxi)            Console.Write(i + " ");    }    Console.WriteLine();     // Printing all the nodes with minimum degree    Console.Write("Nodes with minimum degree : ");    for (int i = 1; i <= n; i++)    {        if (m[i] == mini)            Console.Write(i + " ");    }} // Driver codepublic static void Main(String[] args){    // Count of nodes and edges    int m = 6;     // The edge list    int [,]edges = {{ 1, 2 }, { 1, 3 },                    { 1, 4 }, { 2, 3 },                    { 2, 4 }, { 3, 4 }};     minMax(edges, m, 4);}} // This code is contributed by 29AjayKumar
Output:
Nodes with maximum degree : 1 2 3 4
Nodes with minimum degree : 1 2 3 4

Time Complexity: O(M*logN + N).
Auxiliary Space: O(N).

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