Find the Degree of a Particular vertex in a Graph

5

Given a graph G(V,E) as an adjacency matrix representation and a vertex, find the degree of the vertex v in the graph.

Examples:

0-----1
|\    |
|  \  |
|    \|
2-----3
Input : ver = 0
Output : 3

Input : ver = 1
Output : 2

Algorithm:-

1. Create the graphs adjacency matrix from src to des 
2. For the given vertex then check if 
   a path from this vertices to other exists then 
   increment the degree.
3. Return degree 

Below is the implementation of the approach.

// CPP program to find degree of a vertex.
#include<iostream>
using namespace std;

// structure of a graph
struct graph     
{
    // vertices
    int v;         
    
    // edges
    int e;         
    
    // direction from src to des
    int **dir;     
};

// Returns degree of ver in given graph
int findDegree(struct graph *G, int ver)
{    
    // Traverse through row of ver and count
    // all connected cells (with value 1)
    int degree = 0;         
    for (int i=0; i<G->v; i++)     

        // if src to des is 1 the degree count
        if (G-> dir[ver][i] == 1) 
            degree++;             
    
    return degree;         
}

struct graph *createGraph(int v,int e)
{   
    // G is a pointer of a graph
    struct graph *G = new graph; 
    
    G->v = v;
    G->e = e;
    
    // allocate memory
    G->dir = new int*[v];
    
    for (int i = 0;i < v;i++)
        G->dir[i] = new int[v];
    
    /*  0-----1
        | \   |
        |  \  |
        |   \ |
        2-----3     */
    
    
    //direction from 0
    G->dir[0][1]=1;
    G->dir[0][2]=1;
    G->dir[0][3]=1;
    
    //direction from 1
    G->dir[1][0]=1;
    G->dir[1][3]=1;
    
    //direction from 2
    G->dir[2][0]=1;
    G->dir[2][3]=1;
    
    //direction from 3
    G->dir[3][0]=1;
    G->dir[3][1]=1;
    G->dir[3][2]=1;
    
    return G;
    
}

// Driver code
int main()
{
    int vertices = 4;
    int edges = 5;
    struct graph *G = createGraph(vertices, edges);
    
    // loc is find the degree of 
    // particular vertex
    int ver = 0; 
    
    int degree = findDegree(G, ver);
    cout << degree << "\n";
    return 0;
}

Output:

3

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5 Average Difficulty : 5/5.0
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