Formatted question description: https://leetcode.ca/all/1099.html
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 <= A.length <= 100 1 <= A[i] <= 1000 1 <= K <= 2000
(brute force) O(n^2)
Enumerate i and j, and then find the maximum value less than K.
- Two-level loop traversal, so the time complexity is O(n^2)).
- Only a constant number of traversals are needed, so the space complexity is O(1).