function lonelyinteger(a) { // Write your code here const hash = {}; for(var i = 0; i < a.length; i++){ const number = a[i]; if (hash[number]){ hash[number].push(number); } else { hash[number] = [number]; } } console.log(hash); for (var key in hash){ if (hash[key].length === 1) console.log(key); } } const a = [1,2,3,4,3,2,1]; lonelyinteger(a);