Número de Harshad (o Niven)

Un número entero en base 10 que es divisible por la suma de sus dígitos se dice que es un Número Harshad. Un número n-harshad es un número entero divisible por la suma de su dígito en base n .
A continuación se muestran los primeros Números de Harshad representados en base 10:
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 18, 20………
Dado un número en base 10, nuestra tarea es para comprobar si es un Número Harshad o no.

Ejemplos: 

Input: 3
Output: 3 is a Harshad Number

Input: 18
Output: 18 is a Harshad Number

Input: 15
Output: 15 is not a Harshad Number

1. Extrae todos los dígitos del número usando el operador % y calcula la suma. 
2. Comprueba si el número es divisible por la suma.

A continuación se muestra la implementación de la idea anterior:

// C++ program to check if a number is Harshad
// Number or not.
#include <bits/stdc++.h>
using namespace std;
   
// function to check Harshad Number
bool checkHarshad(int n)
{
    // calculate sum of digits
    int sum = 0;
    for (int temp = n; temp > 0; temp /= 10)
        sum += temp % 10;
   
    // Return true if sum of digits is multiple
    // of n
    return (n % sum == 0);
}
   
// driver program to check above function
int main()
{
    checkHarshad(12) ? cout << "Yes\n" : cout << "No\n";
    checkHarshad(15) ? cout << "Yes\n" : cout << "No\n";
   
    return 0;
}

// Java program to check if a number is Harshad
// Number or not
 
public class GFG {
    // method to check Harshad Number
    static boolean checkHarshad(int n)
    {
        // calculate sum of digits
        int sum = 0;
        for (int temp = n; temp > 0; temp /= 10)
            sum += temp % 10;
 
        // Return true if sum of digits is multiple
        // of n
        return (n % sum == 0);
    }
 
    // Driver program to test above functions
    public static void main(String[] args)
    {
        System.out.println(checkHarshad(12) ? "Yes" : "No");
        System.out.println(checkHarshad(15) ? "Yes" : "No");
    }
}

# Python program to check
# if a number is Harshad
# Number or not.
 
def checkHarshad( n ) :
    sum = 0
    temp = n
    while temp > 0 :
        sum = sum + temp % 10
        temp = temp // 10
    # Return true if sum of
    # digits is multiple of n
    return n % sum == 0
 
# Driver Code
if(checkHarshad(12)) : print("Yes")
else : print ("No")
 
if (checkHarshad(15)) : print("Yes")
else : print ("No")
     
# This code is contributed
# by Nikita Tiwari

// C# program to check if a number is Harshad
// Number or not
using System;
 
public class GFG {
 
    // method to check Harshad Number
    static bool checkHarshad(int n)
    {
 
        // calculate sum of digits
        int sum = 0;
        for (int temp = n; temp > 0; temp /= 10)
            sum += temp % 10;
 
        // Return true if sum of digits is
        // multiple of n
        return (n % sum == 0);
    }
 
    // Driver program to test above functions
    public static void Main()
    {
        Console.WriteLine(checkHarshad(12) ? "Yes" : "No");
 
        Console.WriteLine(checkHarshad(15) ? "Yes" : "No");
    }
}
 
// This code is contributed by vt_m.

<?php
// php program to check if
// a number is Harshad
// Number or not.
 
// function to check
// Harshad Number
function checkHarshad($n)
{
    // calculate sum of digits
    $sum = 0;
    for ($temp = $n; $temp > 0;
                     $temp /= 10)
        $sum += $temp % 10;
 
    // Return true if sum of
    // digits is multiple of n
    return ($n % $sum == 0);
}
 
// Driver Code
$k = checkHarshad(12) ? "Yes\n" : "No\n";
     echo($k);
$k = checkHarshad(15) ? "Yes\n" : "No\n";
     echo($k);
 
// This code is contributed by ajit.
?>

<script>
    // Javascript program to check if a number is Harshad Number or not
     
    // method to check Harshad Number
    function checkHarshad(n)
    {
  
        // calculate sum of digits
        let sum = 0;
        for (let temp = n; temp > 0; temp = parseInt(temp / 10, 10))
            sum += temp % 10;
  
        // Return true if sum of digits is
        // multiple of n
        return (n % sum == 0);
    }
     
    document.write(checkHarshad(12) ? "Yes" + "</br>" : "No" + "</br>");
  
      document.write(checkHarshad(15) ? "Yes" + "</br>" : "No" + "</br>");
         
</script>

Producción : 

Yes
No

Método #2: Usando una string:

• Tenemos que convertir el número dado en una string tomando una nueva variable.
• Atraviese la string, convierta cada elemento en un número entero y agréguelo a la suma.
• Si el número es divisible por la suma, entonces es el número de Harshad.

A continuación se muestra la implementación del enfoque anterior:

// C++ implementation of above approach
#include<bits/stdc++.h>
using namespace std;
 
string checkHarshad(int n)
{
     
    // Converting integer to string
    string st = to_string(n);
     
    // Initialising sum to 0
    int sum = 0;
    int length = st.length();
 
    // Traversing through the string
    for(char i : st)
    {
         
        // Converting character to int
        sum = sum + (i - '0');
    }
     
    // Comparing number and sum
    if (n % sum == 0)
    {
        return "Yes";
    }
    else
    {
        return "No";
    }
}
 
// Driver Code
int main()
{
    int number = 18;
     
    // Passing this number to get result function
    cout << checkHarshad(number) << endl;
}
 
// This code is contributed by rrrtnx

import java.io.*;
// java code to check the given number is Harshad or not
class GFG
{
  // function to check that given number
  // is Harshad or not.
    static String checkHarshad(int n)
    {
       
      // converting the integer to string
        String st = Integer.toString(n);
        int sum = 0;
       
      // calculating total number of digits
      // in a number
        int length=st.length();
       
      // adding the all digits of a number
        for(int i = 0; i < length; i++){
            sum += st.charAt(i)-'0';
        }
       
      // checking that sum is divisior of n or not
        if(n % sum == 0){
           return "YES";
        }
        else{
            return "NO";
        }
    }
   
  // driver code
    public static void main(String args[]){
        int number = 18;
       
      // function call
        System.out.println(checkHarshad(number));
    }
}
 
// This code is contributed by Machhaliya Muhammad

# Python implementation of above approach
def checkHarshad(n):
   
    # Converting integer to string
    st = str(n)
     
    # Initialising sum to 0
    sum = 0
    length = len(st)
 
    # Traversing through the string
    for i in st:
 
        # Converting character to int
        sum = sum + int(i)
         
    # Comparing number and sum
    if (n % sum == 0):
        return "Yes"
    else:
        return "No"
 
 
# Driver Code
number = 18
# passing this number to get result function
print(checkHarshad(number))
 
# This code is contributed by vikkycirus

// C# program to find the radii
// of the three tangent circles
// of equal radius when the radius
// of the circumscribed circle is given
using System;
 
class GFG {
    static String checkHarshad(int n)
    {
 
        // Converting integer to string
        String st = n.ToString();
 
        // Initialising sum to 0
        int sum = 0;
        int length = st.Length;
 
        // Traversing through the string
        foreach(char i in st)
        {
            // Converting character to int
            sum = sum + (i - '0');
        }
 
        // Comparing number and sum
        if (n % sum == 0) {
            return "Yes";
        }
        else {
            return "No";
        }
    }
 
    // Driver code
    public static void Main()
    {
        int number = 18;
 
        // Passing this number to get result function
        Console.WriteLine(checkHarshad(number));
    }
}
 
// This code is contributed by Nidhi goel

<script>
// Javascript implementation of above approach
function checkHarshad(n){
 
    // Converting integer to string
    let st = String(n)
     
    // Initialising sum to 0
    let sum = 0
    let length = st.length
 
    // Traversing through the string
    for(i in st){
        // Converting character to int
        sum = sum + parseInt(i)
    }
         
    // Comparing number and sum
    if (n % sum == 0){
        return "Yes"
    }
    else{
        return "No"
    }
}
 
// Driver Code
let number = 18
// passing this number to get result function
document.write(checkHarshad(number))
 
// This code is contributed by _saurabh_jaiswal
</script>

Yes

Complejidad de tiempo: O(n)

Referencias:  
https://en.wikipedia.org/wiki/Harshad_number
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