# LeetCode 1099. Two Sum Less Than K

## Description

https://leetcode.com/problems/two-sum-less-than-k/

Given an array `nums` of integers and integer `k`, return the maximum `sum` such that there exists `i < j` with `nums[i] + nums[j] = sum` and `sum < k`. If no `i``j` exist satisfying this equation, return `-1`.

Example 1:

```Input: nums = [34,23,1,24,75,33,54,8], k = 60
Output: 58
Explanation: We can use 34 and 24 to sum 58 which is less than 60.
```

Example 2:

```Input: nums = [10,20,30], k = 15
Output: -1
Explanation: In this case it is not possible to get a pair sum less that 15.
```

Constraints:

• `1 <= nums.length <= 100`
• `1 <= nums[i] <= 1000`
• `1 <= k <= 2000`

## Explanation

Sorted and then use two pointers technique.

## Python Solution

``````class Solution:
def twoSumLessThanK(self, nums: List[int], k: int) -> int:

nums = sorted(nums)
i = 0
j = len(nums) - 1

max_sum = -1

while i < j:
if nums[i] + nums[j] >= k:
j -= 1
else:
max_sum = max(max_sum, nums[i] + nums[j])
i += 1

return max_sum``````
• Time Complexity: O(N).
• Space Complexity: O(1).