C++ Programming Code Examples

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Program to Generate a Random UnDirected Graph for a Given Number of Edges



Program to Generate a Random UnDirected Graph for a Given Number of Edges

- This algorithm generates a undirected random graph for the given edges 'e'.
- Basically it implements on a big network.
- The time complexity of this algorithm is O(log(n)).

- This algorithm takes the input of the number of edges 'e'.
- It connects vertexes randomly and generate cyclic, acyclic or disconnected graphs.

#include<iostream>
#include<stdlib.h>
 
// The maximum number of vertex for the sample random graph.
#define NOV 20
 
using namespace std;
 
// A function to generate random graph.
void GenerateRandGraphs(int e)
{
	int i, j, edge[e][2], count;
 
	i = 0;
	// Build a connection between two random vertex.
	while(i < e)
	{
		edge[i][0] = rand()%NOV+1;
		edge[i][1] = rand()%NOV+1;
		i++;
	}
 
	// Print the random graph.
	cout<<"\nThe generated random graph is: ";
	for(i = 0; i < NOV; i++)
	{
		count = 0;
		cout<<"\n\t"<<i+1<<"-> { ";
		for(j = 0; j < e; j++)
		{
			if(edge[j][0] == i+1)
			{
				cout<<edge[j][1]<<"   ";
				count++;
			}
			else if(edge[j][1] == i+1)
			{
				cout<<edge[j][0]<<"   ";
				count++;
			}
			else if(j == e-1 && count == 0)
				cout<<"Isolated Vertex!";
		}
		cout<<" }";
	}	
}
  
int main()
{
	int n, i ,e;
 
	cout<<"Enter the number of edges for the random graphs: ";
	cin>>e;
 
	// A function to generate random undirected graph with e edges.
	GenerateRandGraphs(e);
}