DivideArrayIntoEqualPairs.php

<?php

namespace App;

/**
 * Divide Array Into Equal Pairs
 *
 * You are given an integer array nums consisting of 2 * n integers. You need to divide nums into n pairs such that:
 * - Each element belongs to exactly one pair.
 * - The elements present in a pair are equal.
 * Return true if nums can be divided into n pairs, otherwise return false.
 *
 * Example 1:
 * Input: nums = [3,2,3,2,2,2]
 * Output: true
 * Explanation:
 * There are 6 elements in nums, so they should be divided into 6 / 2 = 3 pairs.
 * If nums is divided into the pairs (2, 2), (3, 3), and (2, 2), it will satisfy all the conditions.
 *
 * Example 2:
 * Input: nums = [1,2,3,4]
 * Output: false
 * Explanation:
 * There is no way to divide nums into 4 / 2 = 2 pairs such that the pairs satisfy every condition.
 *
 * https://leetcode.com/problems/divide-array-into-equal-pairs
 */
class DivideArrayIntoEqualPairs
{
    /**
     * @param int[] $nums
     * @return bool
     */
    public function divideArray(array $nums): bool
    {
        if (count($nums) % 2 !== 0) {
            return false;
        }
        sort($nums);
        foreach (array_chunk($nums, 2) as $chunk) {
            if ($chunk[0] === $chunk[1]) {
                continue;
            }
            return false;
        }
        return true;
    }
}