trie.ts

class Trie {
	private children: Map<string, Trie> = new Map();

	insert(value: string) {
		if (value === "") {
			return;
		}
		const first = value[0];
		if (!first) {
			throw new Error("Expected the first element to not be an empty string.");
		}
		const remainder = value.slice(1);
		let node = this.children.get(first);
		if (!node) {
			node = new Trie();
			this.children.set(first, node);
		}
		node.insert(remainder);
	}

	has(value: string): boolean {
		if (value === "") {
			return this.children.size === 0;
		}

		const first = value[0];
		if (!first) {
			throw new Error("Expected the first element to not be an empty string.");
		}
		const remainder = value.slice(1);
		const node = this.children.get(first);
		if (!node) {
			return false;
		}

		return node.has(remainder);
	}
}

function assert(assertion: boolean, message?: string) {
	if (!assertion) {
		throw new Error(message ?? "Failed");
	}
}

const trie = new Trie();

trie.insert("cool");
trie.insert("nice");
trie.insert("sweet");
trie.insert("amazing");
trie.insert("haha");
trie.insert("canada");

assert(trie.has("cool"));
assert(trie.has("nice"));
assert(trie.has("sweet"));
assert(trie.has("amazing"));

assert(!trie.has("bmazing"));
assert(!trie.has("nmazing"));
assert(!trie.has("cmazing"));
assert(!trie.has("amazin"));
assert(!trie.has("mazing"));
assert(!trie.has("foo"));

assert(trie.has("haha"));
assert(trie.has("canada"));