SeparateDigitsInArray.php

<?php

namespace App;

/**
 * Separate the Digits in an Array
 *
 * Given an array of positive integers nums, return an array answer that consists of the digits of each integer in nums
 * after separating them in the same order they appear in nums.
 * To separate the digits of an integer is to get all the digits it has in the same order.
 * For example, for the integer 10921, the separation of its digits is [1,0,9,2,1].
 *
 * Example 1:
 * Input: nums = [13,25,83,77]
 * Output: [1,3,2,5,8,3,7,7]
 * Explanation:
 * - The separation of 13 is [1,3].
 * - The separation of 25 is [2,5].
 * - The separation of 83 is [8,3].
 * - The separation of 77 is [7,7].
 * answer = [1,3,2,5,8,3,7,7]. Note that answer contains the separations in the same order.
 *
 * Example 2:
 * Input: nums = [7,1,3,9]
 * Output: [7,1,3,9]
 * Explanation: The separation of each integer in nums is itself.
 * answer = [7,1,3,9].
 *
 * https://leetcode.com/problems/separate-the-digits-in-an-array
 */
class SeparateDigitsInArray
{
    /**
     * @param int[] $nums
     * @return int[]
     */
    public function separateDigits(array $nums): array
    {
        $result = [];
        foreach ($nums as $num) {
            $result = [...$result, ...$this->numberToDigits($num)];
        }
        return $result;
    }

    /**
     * Returns an array of digits of a number
     * @param int $number
     * @return int[]
     */
    private function numberToDigits(int $number): array
    {
        $digits = [];
        while ($number > 0) {
            $digits[] = $number % 10;
            $number = (int)($number / 10);
        }
        return array_reverse($digits);
    }
}