exercism/zig/armstrong-numbers/armstrong_numbers.zig

const std = @import("std");

pub fn isArmstrongNumber(num: u128) bool {
    var digits: u8 = 0;
    var digits_rem = num;
    while (digits_rem != 0) : (digits_rem /= 10) {
        digits += 1;
    }

    var sum: u128 = 0;
    var num_rem = num;
    while (num_rem != 0) : (num_rem /= 10) {
        sum += std.math.pow(u128, num_rem % 10, digits);
    }

    return num == sum;
}