public class Solution
extends Object
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:**
* 1 <= nums.length <= 105
* 1 <= nums[i] <= 109
* 1 <= k <= 109