Armstrong Number

Given an integer n, return true if and only if it is an Armstrong number.

The k-digit number n is an Armstrong number if and only if the kᵗʰ power of each digit sums to n.

Example 1:

Input: n = 153

Output: true

Explanation:
153 is a 3-digit number, and 153 = 1³ + 5³ + 3³.

Example 2:

Input: n = 123

Output: false

Explanation:
123 is a 3-digit number, and 123 != 1³ + 2³ + 3³ = 36.

Constraints:

• 1 <= n <= 10⁸