TCS Coding Practice Question | Check Armstrong Number

Given a number, the task is to check if this number is Armstrong or not using Command Line Arguments. A positive integer of n digits is called an Armstrong number of order n (order is number of digits) if.

abcd... = pow(a, n) + pow(b, n) + pow(c, n) + pow(d, n) + .... 

Example:

Input: 153
Output: Yes
153 is an Armstrong number.
1*1*1 + 5*5*5 + 3*3*3 = 153

Input: 120
Output: No
120 is not a Armstrong number.
1*1*1 + 2*2*2 + 0*0*0 = 9

Input: 1253
Output: No
1253 is not a Armstrong Number
1*1*1*1 + 2*2*2*2 + 5*5*5*5 + 3*3*3*3 = 723

Input: 1634
Output: Yes
1*1*1*1 + 6*6*6*6 + 3*3*3*3 + 4*4*4*4 = 1634

Approach:

  • Since the number is entered as Command line Argument, there is no need for a dedicated input line
  • Extract the input number from the command line argument
  • This extracted number will be in String type.
  • Convert this number into integer type and store it in a variable, say num
  • Count number digits (or find order) of the number num and store it in a variable, say n.
  • For every digit r in input number num, compute rn.
  • If sum of all such values is equal to num
  • If they are not same, the number is not Armstrong
  • If they are same, the number is a Armstrong

Program:

C

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// C program to check if a number is Armstrong
// using command line arguments
  
#include <stdio.h>
#include <stdlib.h> /* atoi */
  
// Function to calculate x raised to the power y
int power(int x, unsigned int y)
{
    if (y == 0)
        return 1;
    if (y % 2 == 0)
        return power(x, y / 2) * power(x, y / 2);
    return x * power(x, y / 2) * power(x, y / 2);
}
  
// Function to calculate order of the number
int order(int x)
{
    int n = 0;
    while (x) {
        n++;
        x = x / 10;
    }
    return n;
}
  
// Function to check whether the given number is
// Armstrong number or not
int isArmstrong(int x)
{
    // Calling order function
    int n = order(x);
    int temp = x, sum = 0;
    while (temp) {
  
        int r = temp % 10;
        sum += power(r, n);
        temp = temp / 10;
    }
  
    // If satisfies Armstrong condition
    if (sum == x)
        return 1;
    else
        return 0;
}
  
// Driver code
int main(int argc, char* argv[])
{
  
    int num, res = 0;
  
    // Check if the length of args array is 1
    if (argc == 1)
        printf("No command line arguments found.\n");
  
    else {
  
        // Get the command line argument and
        // Convert it from string type to integer type
        // using function "atoi( argument)"
        num = atoi(argv[1]);
  
        // Check if it is Armstrong
        res = isArmstrong(num);
  
        // Check if res is 0 or 1
        if (res == 0)
            // Print No
            printf("No\n");
        else
            // Print Yes
            printf("Yes\n");
    }
    return 0;
}

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Java

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// Java program to check if a number is Armstrong
// using command line arguments
  
class GFG {
  
    // Function to calculate x
    // raised to the power y
    public static int power(int x, long y)
    {
        if (y == 0)
            return 1;
        if (y % 2 == 0)
            return power(x, y / 2) * power(x, y / 2);
        return x * power(x, y / 2) * power(x, y / 2);
    }
  
    // Function to calculate order of the number
    public static int order(int x)
    {
        int n = 0;
        while (x != 0) {
            n++;
            x = x / 10;
        }
        return n;
    }
  
    // Function to check whether the given number is
    // Armstrong number or not
    public static int isArmstrong(int x)
    {
        // Calling order function
        int n = order(x);
        int temp = x, sum = 0;
        while (temp != 0) {
            int r = temp % 10;
            sum = sum + power(r, n);
            temp = temp / 10;
        }
  
        // If satisfies Armstrong condition
        if (sum == x)
            return 1;
        else
            return 0;
    }
  
    // Driver code
    public static void main(String[] args)
    {
  
        // Check if length of args array is
        // greater than 0
        if (args.length > 0) {
  
            // Get the command line argument and
            // Convert it from string type to integer type
            int num = Integer.parseInt(args[0]);
  
            // Get the command line argument
            // and check if it is Armstrong
            int res = isArmstrong(num);
  
            // Check if res is 0 or 1
            if (res == 0)
                // Print No
                System.out.println("No\n");
            else
                // Print Yes
                System.out.println("Yes\n");
        }
        else
            System.out.println("No command line "
                               + "arguments found.");
    }
}

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Output:

  • In C:

  • In Java:



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