AlgoDaily 20: Uniqueness of Arrays

https://algodaily.com/challenges/uniqueness-of-arrays

This is pretty trivial with the Set class in ECMAScript 2015.

function uniques(items) {
	return [...new Set(items)];
}

If that seems like cheating, then we can achieve this with a hash map and a new array:

function uniques(items) {
	const seen = {};
	const unique = [];
	for (let x of items) {
		if (seen[x] === undefined) {
			unique.push(x);
			seen[x] = true;
		}
	}
	return unique;
}

This is O(n).

View post: AlgoDaily 20: Uniqueness of Arrays