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++

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// 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;
}

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Java














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// 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)); 


    } 


  


} 



















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Python 3














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# 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 



















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C#














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// 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 



















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PHP














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<?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 


?> 



















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Output:


15







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