Program to find total number of edges in a Complete Graph

Given N number of vertices of a Graph. The task is to find the total number of edges possible in a complete graph of N vertices.

Complete Graph: A Complete Graph is a graph in which every pair of vertices is connected by an edge.

Examples:



Input : N = 3
Output : Edges = 3

Input : N = 5
Output : Edges = 10

The total number of possible edges in a complete graph of N vertices can be given as,

Total number of edges in a complete graph of N vertices = ( n * ( n – 1 ) ) / 2

Example 1: Below is a complete graph with N = 5 vertices.

The total number of edges in the above complete graph = 10 = (5)*(5-1)/2.

Below is the implementation of the above idea:

C++

filter_none

edit
close

play_arrow

link
brightness_4
code

// C++ implementation to find the
// number of edges in a complete graph
  
#include <bits/stdc++.h>
using namespace std;
  
// Function to find the total number of
// edges in a complete graph with N vertices
int totEdge(int n)
{
    int result = 0;
  
    result = (n * (n - 1)) / 2;
  
    return result;
}
  
// Driver Code
int main()
{
    int n = 6;
  
    cout << totEdge(n);
  
    return 0;
}

chevron_right


Java

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java implementation to find the
// number of edges in a complete graph
  
class GFG {
      
// Function to find the total number of
// edges in a complete graph with N vertices
static int totEdge(int n)
{
    int result = 0;
  
    result = (n * (n - 1)) / 2;
  
    return result;
}
  
    // Driver Code
    public static void main(String []args)
    {
        int n = 6;
        System.out.println(totEdge(n));
    }
  
}

chevron_right


Python 3

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python 3 implementation to  
# find the number of edges 
# in a complete graph 
  
# Function to find the total 
# number of edges in a complete
# graph with N vertices
def totEdge(n) :
  
    result = (n * (n - 1)) // 2
  
    return result
              
# Driver Code
if __name__ == "__main__" :
  
    n = 6
  
    print(totEdge(n))
  
# This code is contributed
# by ANKITRAI1

chevron_right


C#

filter_none

edit
close

play_arrow

link
brightness_4
code

// C# implementation to find 
// the number of edges in a
// complete graph
using System;
  
class GFG 
{
      
// Function to find the total 
// number of edges in a complete 
// graph with N vertices
static int totEdge(int n)
{
    int result = 0;
  
    result = (n * (n - 1)) / 2;
  
    return result;
}
  
// Driver Code
public static void Main()
{
    int n = 6;
    Console.Write(totEdge(n));
}
}
  
// This code is contributed 
// by ChitraNayal

chevron_right


PHP

filter_none

edit
close

play_arrow

link
brightness_4
code

<?php
// PHP implementation to find 
// the number of edges in a 
// complete graph 
  
// Function to find the total 
// number of edges in a complete
// graph with N vertices 
function totEdge($n
    $result = 0; 
  
    $result = ($n * ($n - 1)) / 2; 
  
    return $result
  
// Driver Code 
$n = 6; 
echo totEdge($n); 
  
// This code is contributed
// by Shivi_Aggarwal
?>

chevron_right


Output:

15


My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.