Armstrong Number — LeetCode 1134 Python Solution

The problem

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

Input

n = 153

Output

true

Explanation

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

Python solution

class Solution:
    def isArmstrong(self, n: int) -> bool:
        k = len(str(n))
        s, x = 0, n
        while x:
            s += (x % 10) ** k
            x //= 10
        return s == n

Complexity

Pattern: Math and Number Theory

Find the closed form, the invariant, or the modular identity — and skip the loop entirely. LeetCode 1134. Armstrong Number is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Math.

The math and number theory guide has the Python template for the pattern and the 485 LeetCode problems that use it.

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