// Naive function hasPairWithSum(arr, sum){ var len = arr.length; for(var i =0; i<len-1; i++){ for(var j = i+1;j<len; j++){ if (arr[i] + arr[j] === sum) return true; } } return false; } // Better function hasPairWithSum2(arr, sum){ const mySet = new Set(); const len = arr.length; for (let i = 0; i < len; i++){ if (mySet.has(arr[i])) { return true; } mySet.add(sum - arr[i]); } return false; } hasPairWithSum2([6,4,3,2,1,7], 9)