RemoveDuplicatesSortedArray.php

<?php

namespace App;

/**
 * Remove Duplicates from Sorted Array
 *
 * Given an integer array nums sorted in non-decreasing order, remove the duplicates in-place such that each unique
 * element appears only once. The relative order of the elements should be kept the same.
 * Since it is impossible to change the length of the array in some languages, you must instead have the result be
 * placed in the first part of the array nums. More formally, if there are k elements after removing the duplicates,
 * then the first k elements of nums should hold the final result. It does not matter what you leave beyond the
 * first k elements. Return k after placing the final result in the first k slots of nums.
 * Do not allocate extra space for another array. You must do this by modifying the input array in-place with O(1)
 * extra memory.
 * Example 1:
 * Input: nums = [1,1,2]
 * Output: 2, nums = [1,2,_]
 * Explanation: Your function should return k = 2, with the first two elements of nums being 1 and 2 respectively.
 * It does not matter what you leave beyond the returned k (hence they are underscores).
 * Example 2:
 * Input: nums = [0,0,1,1,1,2,2,3,3,4]
 * Output: 5, nums = [0,1,2,3,4,_,_,_,_,_]
 * Explanation: Your function should return k = 5, with the first five elements of nums being 0, 1, 2, 3, and
 * 4 respectively. It does not matter what you leave beyond the returned k (hence they are underscores).
 *
 * https://leetcode.com/problems/remove-duplicates-from-sorted-array
 */
class RemoveDuplicatesSortedArray
{
    /**
     * @param array<array-key, int> $nums
     * @return int
     */
    public function removeDuplicates(array &$nums): int
    {
        $previousNumber = $nums[0];
        for ($i = 1; $i < count($nums); $i++) {
            if ($previousNumber === $nums[$i]) {
                array_splice($nums, $i, 1);
                $i--;
            }
            $previousNumber = $nums[$i];
        }
        return count($nums);
    }
}