Número superperfecto

Dado un entero n. Comprueba si el número n es un número superperfecto o no. Un número superperfecto es un entero positivo que satisface σ 2 (n) = σ(σ(n)) = 2n, donde σ es la función sumatoria del divisor
 

Input: n = 16
Output: yes
Explanation:
16 is a superperfect number as σ(16) = 1 + 2 + 4 + 8 + 16 = 31,
and σ(31) = 1 + 31 = 32, 
thus σ(σ(16)) = 32 = 2 × 16.

Input: n = 8
Output: no 
Explanation:
σ(8) = 1 + 2 + 4 + 8 = 15
and σ(15) = 1 + 3 + 5 + 15 = 24
thus ( σ(σ(8)) = 24 ) ≠ (2 * 8 = 26)
Le recomendamos encarecidamente que haga clic aquí y lo practique antes de pasar a la solución.

La idea es sencillamente sencilla. Simplemente iteramos de 1 a sqrt (n) y encontramos la suma de todos los divisores de n, llamemos a esta suma como n1. Ahora nuevamente necesitamos iterar de 1 a sqrt(n1) y encontrar la suma de todos los divisores. Después de eso, solo tenemos que comprobar si la suma resultante es igual a 2*n o no. 
 

C++

// C++ program to check whether number is
// superperfect or not
#include<bits/stdc++.h>
using namespace std;
 
// Function to calculate sum of all divisors
int divSum(int num)
{
    // Final result of summation of divisors
    int result = 0;
 
    // find all divisors which divides 'num'
    for (int i=1; i*i <= num; ++i)
    {
        // if 'i' is divisor of 'num'
        if (num%i == 0)
        {
            // if both divisors are same then add
            // it only once else add both
            if (i == (num/i))
                result += i;
            else
                result += (i + num/i);
        }
    }
 
    return result;
}
 
// Returns true if n is Super Perfect else false.
bool isSuperPerfect(int n)
{
    // Find the sum of all divisors of number n
    int n1 = divSum(n);
 
    // Again find the sum of all divisors of n1
    // and check if sum is equal to n1
    return (2*n == divSum(n1));
}
 
//Driver code
int main()
{
    int n = 16;
    cout << (isSuperPerfect(n) ? "Yes\n" : "No\n");
 
    n = 6;
    cout << (isSuperPerfect(n) ? "Yes\n" : "No\n");
    return 0;
}

Java

// Java program to check whether number is
// superperfect or not
 
public class Divisors
{
    // Function to calculate sum of all divisors
    static int divSum(int num)
    {
        // Final result of summation of divisors
        int result = 0;
         
        // find all divisors which divides 'num'
        for (int i=1; i*i <= num; ++i)
        {
            // if 'i' is divisor of 'num'
            if (num%i == 0)
            {
                // if both divisors are same then add
                // it only once else add both
                if (i == (num/i))
                    result += i;
                else
                    result += (i + num/i);
            }
        }
        return result;
    }
     
    // Returns true if n is Super Perfect else false.
    static boolean isSuperPerfect(int n)
    {
        // Find the sum of all divisors of number n
        int n1 = divSum(n);
        // Again find the sum of all divisors of n1
        // and check if sum is equal to n1
        return (2*n == divSum(n1));
    }
     
    public static void main (String[] args)
    {
        int n = 16;
        System.out.printf((isSuperPerfect(n) ? "Yes\n" : "No\n"));
         
        n = 6;
        System.out.printf((isSuperPerfect(n) ? "Yes\n" : "No\n"));
    }
}
 
// This code is contributed by Saket Kumar

Python3

# Python program to check whether number
# is superperfect or not
import math
 
# Function to calculate sum of all divisors
def divSum(num):
 
    # Final result of summation of divisors
    result = 0
 
    # find all divisors which divides 'num'
    sq = int(math.sqrt(num))
    for i in range(1, sq+1):
 
        # if 'i' is divisor of 'num'
        if num %i == 0:
 
            # if both divisors are same then add
            # it only once else add both
            if i == (num//i):
                result += i
            else:
                result += (i + num//i)
 
 
 
    return result
 
# Returns true if n is superperfect else false
def isSuperPerfect(n):
 
    # Find the sum of all divisors of number n
    n1 = divSum(n)
 
    # Again find the sum of all divisors of n1
    return divSum(n1) == 2*n
 
 
#Driver code
n = 16
print ('Yes' if isSuperPerfect(n) else 'No')
 
n = 6
print ('Yes' if isSuperPerfect(n) else 'No')

C#

// C# program to check whether number is
// superperfect or not
using System;
 
class Divisors
{
    // Function to calculate sum of all divisors
    static int divSum(int num)
    {
        // Final result of summation of divisors
        int result = 0;
         
        // find all divisors which divides 'num'
        for (int i = 1; i * i <= num; ++i)
        {
            // if 'i' is divisor of 'num'
            if (num % i == 0)
            {
                // if both divisors are same then add
                // it only once else add both
                if (i == (num / i))
                    result += i;
                else
                    result += (i + num / i);
            }
        }
        return result;
    }
     
    // Returns true if n is Super Perfect else false.
    static bool isSuperPerfect(int n)
    {
        // Find the sum of all divisors of number n
        int n1 = divSum(n);
        // Again find the sum of all divisors of n1
        // and check if sum is equal to n1
        return (2 * n == divSum(n1));
    }
     
    public static void Main ()
    {
        int n = 16;
        Console.WriteLine((isSuperPerfect(n) ? "Yes" : "No"));
         
        n = 6;
        Console.WriteLine((isSuperPerfect(n) ? "Yes" : "No"));
    }
}
 
// This code is contributed by vt_m.

PHP

<?php
// PHP program to check whether
// number is superperfect or not
 
// Function to calculate
// sum of all divisors
function divSum($num)
{
     
    // Final result of
    // summation of divisors
    $result = 0;
 
    // find all divisors
    // which divides 'num'
    for ($i = 1; $i * $i <= $num; ++$i)
    {
         
        // if 'i' is divisor
        // of 'num'
        if ($num % $i == 0)
        {
             
            // if both divisors
            // are same then add
            // it only once else
            // add both
            if ($i == ($num / $i))
                $result += $i;
            else
                $result += ($i + $num/$i);
        }
    }
 
    return $result;
}
 
// Returns true if n is
// Super Perfect else false.
function isSuperPerfect($n)
{
     
    // Find the sum of all
    // divisors of number n
    $n1 = divSum($n);
 
    // Again find the sum
    // of all divisors of n1
    // and check if sum is
    // equal to n1
    return (2 * $n == divSum($n1));
}
 
    // Driver code
    $n = 16;
    $hh = (isSuperPerfect($n) ? "Yes\n" : "No\n");
        echo($hh);
 
    $n = 6;
    $hh=(isSuperPerfect($n) ? "Yes\n" : "No\n");
        echo($hh);
 
// This code is contributed by AJit
?>

Javascript

<script>
 
// JavaScript program for the above approach
  
    // Function to calculate sum of all divisors
    function divSum(num)
    {
     
        // Final result of summation of divisors
        let result = 0;
           
        // find all divisors which divides 'num'
        for (let i = 1; i * i <= num; ++i)
        {
         
            // if 'i' is divisor of 'num'
            if (num % i == 0)
            {
             
                // if both divisors are same then add
                // it only once else add both
                if (i == (num/i))
                    result += i;
                else
                    result += (i + num/i);
            }
        }
        return result;
    }
       
    // Returns true if n is Super Perfect else false.
    function isSuperPerfect(n)
    {
     
        // Find the sum of all divisors of number n
        let n1 = divSum(n);
         
        // Again find the sum of all divisors of n1
        // and check if sum is equal to n1
        return (2*n == divSum(n1));
    }
 
// Driver Code   
      let n = 16;
      document.write((isSuperPerfect(n) ? "Yes\n" : "No\n") + "<br />");
           
       n = 6;
      document.write((isSuperPerfect(n) ? "Yes\n" : "No\n") + "<br />");
 
// This code is contributed by splevel62.
</script>
Output:
Yes
No

Complejidad temporal: O(sqrt(n + n1)) donde n1 es la suma de los divisores de n. 
Espacio auxiliar: O(1)
Datos sobre los supernúmeros: 
 

  1. Si n es un número superperfecto par, entonces n debe ser una potencia de 2, es decir, 2 k tal que 2 k+1 – 1 es un primo de Mersenne .
  2. No se sabe si existen números superperfectos impares. Un número superperfecto impar n tendría que ser un número cuadrado tal que n o σ(n) sea divisible por al menos tres números primos distintos. No hay números superperfectos impares por debajo de 7×10 24

Referencia:  
https://en.wikipedia.org/wiki/Superperfect_number
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Artículo escrito por GeeksforGeeks-1 y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA

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