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# Max Number of K-Sum Pairs

Updated: Jan 18, 2021

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

Solution:

```class Solution {
public int maxOperations(int[] nums, int k) {
int left,right,count=0;
Arrays.sort(nums);
left=0;
right=nums.length-1;
while(left<right)
{
if(nums[left]+nums[right]==k)
{
count++;
left++;
right--;
}
else if(nums[left]+nums[right]>k)
{
right--;
}
else
{
left++;
}
}
return count;
}
}

```