Sergio Alves

You are given an integer array nums and an integer k.

In one operation, you can pick two numbers from the array whose sum equals k and remove them from the array.

Return the maximum number of operations you can perform on the array.

Example 1:

Input: nums = [1,2,3,4], k = 5
Output: 2
Explanation: Starting with nums = [1,2,3,4]:
- Remove numbers 1 and 4, then nums = [2,3]
- Remove numbers 2 and 3, then nums = []
There are no more pairs that sum up to 5, hence a total of 2 operations.

Example 2:

Input: nums = [3,1,3,4,3], k = 6
Output: 1
Explanation: Starting with nums = [3,1,3,4,3]:
- Remove the first two 3's, then nums = [1,4,3]
There are no more pairs that sum up to 6, hence a total of 1 operation.

Constraints:

• 1 <= nums.length <= 105
• 1 <= nums[i] <= 109
• 1 <= k <= 109

PHP Code

class Solution {

    /**
     * @param Integer[] $nums
     * @param Integer $k
     * @return Integer
     */
    function maxOperations($nums, $k) {
        $count = 0;
        $n = 1;
        for ($i=0;$i<count($nums); $i++) {
            for ($j=$n; $j<count($nums); $j++) {
                $r = $nums[$i] + $nums[$j];
                if ($r == $k && $nums[$i] > 0 && $nums[$j] > 0) {
                    $nums[$i] = 0;
                    $nums[$j] = 0;
                    $count++;
                }
            }
            $n++;
        }
        return $count;
    }
}