1679 - Max Number of K-Sum Pairs.

Medium

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:

• <code>1 <= nums.length <= 10⁵</code>

• <code>1 <= numsi<= 10⁹</code>

• <code>1 <= k <= 10⁹</code>