Neon Number in C++

Neon Number in C++

Neon Number :

A number whose sum of digits of square of the number is equal to the number is called neon number. For example, number 9 is a neon number as its sum of square of its digits is 81 and the sum of the digits is 9. i.e. 9 is a neon number. There are only 3 neon numbers. They are 0, 1, and 9.

Example 1 : 9

      9

=>  9 * 9

=>   81
=>  8+1
=>  9 = Number = 9 , Hence 9 is a Neon number.

Example 2 : 1

      1

=  1 * 1

=   1 = 1 = Number, Hence 1 is an a Neon number.

Example 3 : 7

      7

=  7 * 7

=   49
= 4+9
=13  != 7 , Hence 7 is not a Neon number.

Algorithm to check whether a given number is a Neon Number or not:

Step 1: Accept a number.

Step 2: Calculate the square of a number and store it in a variable (say square).
Step 3: Find the sum of digits of the square of a number and store it in a variable (say sum).
Step 4: If the sum is equal to the accepted number then display "Neon number" else display "Not Neon Number".

Step 5: Stop

Sample Input and Output:

Input 1:    Enter number here --> 1
Output 1: The given number 1 is a Neon number

Input 2:    Enter number here --> 9
Output 2: The given number 9 is a Neon number

Input 3:    Enter number here --> 7
Output 3: The given number 7 is not a Neon number

Question: Write a program in C++ to check whether a given number is a Neon number or not.

Code 1: 

// Program to check whether a given number is a Neon number or not
#include <iostream>
using namespace std;
int main()
{
    int number;
    cout << "Enter number here --> ";
    cin >> number;
    int square = number * number;
    int sum = 0;
    while (square > 0)
    {
        int lastDigit = square % 10;
        sum = sum + lastDigit;
        square = square / 10;
    }
    if (sum == number)
        cout << "The given number " << number << " is a Neon number";
    else
        cout << "The given number " << number << " is not a Neon number";
    return 0;
}

Code 2: 

// Program to check whether a given number is a Neon number or not
#include <iostream>
#include <string> // To use to_string function
using namespace std;
int main()
{
    int number;
    cout << "Enter number here --> ";
    cin >> number;
    int square = number * number;
    string sq = to_string(square);
    int sum = 0;
    for (int i = 0; i < sq.length(); i++)
    {
        int currentDigit = sq.at(i) - 48;
        sum = sum + currentDigit;
    }
    if (sum == number)
        cout << "The given number " << number << " is a Neon number";
    else
        cout << "The given number " << number << " is not a Neon number";
    return 0;
}

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