A number with k digits is an Armstrong number if the sum of each digit raised to the power k equals the number itself. For instance 153 has 3 digits and 1**3 + 5**3 + 3**3 = 1 + 125 + 27 = 153. Write is_armstrong(n) that returns True when n is an Armstrong number and False otherwise. Single-digit numbers (including 0) are all Armstrong numbers.
Examples
Input: n = 153
Output: True
Input: n = 10
Output: False
Explanation: 1**2 + 0**2 = 1, which is not 10.
Constraints
0 <= n <= 10**9
Goals
- Use one loop to count digits and another to process them
- Compare an accumulated value with the original number