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 the 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 the number of digits (or find the order) of the number num and store it in a variable, say n.
• For every digit r in input number num, compute rⁿ.
• If the sum of all such values is equal to num
• If they are not same, the number is not Armstrong
• If they are the same, the number is an Armstrong Number.

Program: 

Output:

• In C: 👁 Image
  
• In Java: 👁 Image
  

Time Complexity: O (log N)
Auxiliary Space: O (1)