Given an integer n, the task is to find the nth hexagonal number . The nth hexagonal number Hn is the number of distinct dots in a pattern of dots consisting of the outlines of regular hexagons with sides up to n dots when the hexagons are overlaid so that they share one vertex.{Source : wiki}
Input: n = 2
Output: 6
Input: n = 5
Output: 45
Input: n = 7
Output: 91
In general, a polygonal number (triangular number, square number, etc) is a number represented as dots or pebbles arranged in the shape of a regular polygon. The first few pentagonal numbers are 1, 5, 12, etc.
If s is the number of sides in a polygon, the formula for the nth s-gonal number P (s, n) is
nth s-gonal number P(s, n) = (s - 2)n(n-1)/2 + n
If we put s = 6, we get
n'th Hexagonal number Hn = 2(n*n)-n
= n(2n - 1)
C++
#include<bits/stdc++.h>
using namespace std;
int hexagonalNum( int n){
return n*(2*n - 1);
}
int main(){
int n = 10;
cout << "10th Hexagonal Number is " << hexagonalNum(n) << endl;
return 0;
}
|
C
#include <stdio.h>
#include <stdlib.h>
int hexagonalNum( int n)
{
return n*(2*n - 1);
}
int main()
{
int n = 10;
printf ( "10th Hexagonal Number is = %d" ,
hexagonalNum(n));
return 0;
}
|
Java
class Hexagonal
{
int hexagonalNum( int n)
{
return n*( 2 *n - 1 );
}
}
public class GeeksCode
{
public static void main(String[] args)
{
Hexagonal obj = new Hexagonal();
int n = 10 ;
System.out.printf( "10th Hexagonal number is = "
+ obj.hexagonalNum(n));
}
}
|
Python3
def hexagonalNum( n ):
return n * ( 2 * n - 1 )
n = 10
print ( "10th Hexagonal Number is = " , hexagonalNum(n))
|
C#
using System;
class GFG {
static int hexagonalNum( int n)
{
return n * (2 * n - 1);
}
public static void Main()
{
int n = 10;
Console.WriteLine( "10th Hexagonal"
+ " number is = " + hexagonalNum(n));
}
}
|
PHP
<?php
function hexagonalNum( $n )
{
return $n * (2 * $n - 1);
}
$n = 10;
echo ( "10th Hexagonal Number is " .
hexagonalNum( $n ));
?>
|
Javascript
<script>
function hexagonalNum(n)
{
return n * (2 * n - 1);
}
var n = 10;
document.write( "10th Hexagonal number is = " +
hexagonalNum(n));
</script>
|
Output:
10th Hexagonal Number is = 190
Time complexity: O(1) since performing constant operations
Auxiliary space: O(1) since it is using constant variables
Reference:https://en.wikipedia.org/wiki/Hexagonal_number
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Last Updated :
01 Sep, 2022
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