C++ Exercises: Check whether a given number is a Kaprekar number or not

Last update on December 20 2024 12:31:02 (UTC/GMT +8 hours)

Write a program in C++ to check whether a given number is a Kaprekar number or not.

Visual Presentation:

Sample Solution:

C++ Code :

#include<bits/stdc++.h> // Include the entire standard C++ library
using namespace std;

bool chkkaprekar(int n)
{
    if (n == 1)
        return true; // If the number is 1, it's considered a Kaprekar number

    int sqr_n = n * n; // Calculate the square of the number
    int ctr_digits = 0; // Variable to count the number of digits in the square

    // Calculate the number of digits in the square of n
    while (sqr_n)
    {
        ctr_digits++; // Increment the digit count
        sqr_n /= 10; // Reduce the number by one digit
    }

    sqr_n = n * n; // Reset sqr_n to n squared
    for (int r_digits = 1; r_digits < ctr_digits; r_digits++)
    {
        int eq_parts = pow(10, r_digits); // Determine the equal parts for the comparison

        if (eq_parts == n)
            continue; // If equal parts match the number, skip the comparison

        // Calculate the sum of two parts after splitting the square number
        int sum = sqr_n / eq_parts + sqr_n % eq_parts;

        if (sum == n)
            return true; // If the sum matches the original number, it's a Kaprekar number
    }
    return false; // If no condition satisfies, it's not a Kaprekar number
}

int main()
{
    int kpno; // Declare a variable for the input number

    cout << "\n\n Check whether a given number is a Kaprekar number: \n"; // Display a message for user
    cout << " -------------------------------------------------------\n";

    cout << " Input a number: "; // Prompt the user to input a number
    cin >> kpno; // Read the input number

    // Check if the entered number is a Kaprekar number and display the result
    chkkaprekar(kpno) ? cout << kpno << " is a Kaprekar number. " : cout << kpno << " is not a Kaprekar number.";
    cout << endl;
}

Sample Output:

 Check whether a given number is a Kaprekar number:                    
 -------------------------------------------------------               
 Input a number: 45.                                                   
45 is a Kaprekar number. 

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