Tags: "leetcode", "two-pointers", access_time 1-min read

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Two Sum Less Than K

Created: August 22, 2019 by [lek-tin]

Last updated: August 22, 2019

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

Example 1

Input: A = [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: A = [10,20,30], K = 15
Output: -1
Explanation:
In this case it's not possible to get a pair sum less that 15.

Note

  1. 1 <= A.length <= 100
  2. 1 <= A[i] <= 1000
  3. 1 <= K <= 2000

Solution

class Solution:
    def twoSumLessThanK(self, A: List[int], K: int) -> int:
        A.sort()
        left, right = 0 , len(A)-1
        result = -1

        while left < right:
            temp = A[left] + A[right]
            if K <= temp:
                right -= 1
            else:
                result = max(result, temp)
                left += 1

        return result