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# 1679. Max Number of K-Sum Pairs

<https://leetcode.com/problems/max-number-of-k-sum-pairs>

## Description

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`

## ac

```java
```