1099. Two Sum Less Than K.js

// 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

/**
 * @param {number[]} A
 * @param {number} K
 * @return {number}
 */

// Sorting + Two Pointers
// Time O(n log n)
// Space O(1)
const twoSumLessThanK = (A, K) => {
  A.sort((a, b) => a - b);
  let max = -1;
  let l = 0;
  let r = A.length - 1;
  while (l < r) {
    const sum = A[l] + A[r];
    if (sum < K) {
      max = Math.max(max, sum);
      l++;
    } else {
      r--;
    }
  }
  return max;
};