Pair Sum – Unsorted

Given an unsorted array of integers nums and a target integer target, return true if there exist two numbers in the array that add up to the target.

Input:  nums = [2, 7, 11, 15], target = 9
Output: true

function hasPairSum(nums, target) {
  const seen = new Set();
  
  for (const num of nums) {
    if (seen.has(target - num)) return true;
    seen.add(num);
  }
  return false;
}