FindNumbersWithEvenNumberOfDigits.php

<?php

namespace App;

/**
 * Find Numbers with Even Number of Digits
 *
 * Given an array nums of integers, return how many of them contain an even number of digits.
 *
 * Example 1:
 * Input: nums = [12,345,2,6,7896]
 * Output: 2
 * Explanation:
 * 12 contains 2 digits (even number of digits).
 * 345 contains 3 digits (odd number of digits).
 * 2 contains 1 digit (odd number of digits).
 * 6 contains 1 digit (odd number of digits).
 * 7896 contains 4 digits (even number of digits).
 * Therefore, only 12 and 7896 contain an even number of digits.
 *
 * Example 2:
 * Input: nums = [555,901,482,1771]
 * Output: 1
 * Explanation:
 * Only 1771 contains an even number of digits.
 *
 * https://leetcode.com/problems/find-numbers-with-even-number-of-digits
 */
class FindNumbersWithEvenNumberOfDigits
{
    /**
     * @param array<array-key, int> $nums
     * @return int
     */
    public function findNumbers(array $nums): int
    {
        $evenDigits = 0;
        foreach ($nums as $num) {
            $numDigits = $this->findNumberOfDigits($num);
            if ($numDigits % 2 === 0) {
                $evenDigits++;
            }
        }
        return $evenDigits;
    }

    private function findNumberOfDigits(int $number): int
    {
        $numDigits = 0;
        while ($number > 0) {
            $number = (int)($number / 10);
            $numDigits++;
        }
        return $numDigits;
    }
}