const removeExactlyOneDuplicate = (arr) => {
let map = new Map();
for (let i = 0; i < arr.length; i++) {
if (!map.has(arr[i])) {
map.set(arr[i], 1);
} else {
return arr[i];
}
}
};
// console.log(removeExactlyOneDuplicate([1, 3, 4, 2, 2]));
console.log(removeExactlyOneDuplicate([3, 1, 3, 4, 2]));