Max Number of K-Sum Pairs

arrayhash tabletwo pointers

Problem Statement

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 .

Examples

Example 1

Input: nums = [1,2,3,4], k = 5
Output: 2
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
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 <= 10 ^5

1 <= nums[i] <= 10 ^9

1 <= k <= 10 ^9

🤔

Medium

Difficulty

Topic Info

ModuleDSA

CategoryArray

Sub-topicHash Table