day 3

day-3/day3.ts

@@ -0,0 +1,26 @@
+import * as R from "remeda";
+
+const regex = new RegExp(/mul\((\d{1,3},\d{1,3}?)\)/g);
+
+export function day3(input: string) {
+	const matches = input.matchAll(regex);
+	const numberPairs = [];
+	for (const match of matches) {
+		numberPairs.push(match[1].split(",").map((v) => Number.parseInt(v, 10)));
+	}
+	return R.pipe(
+		numberPairs,
+		R.map(([a, b]) => a * b),
+		R.sum,
+	) as unknown as number;
+}
+
+export function day3part2(input: string) {
+	const parts = input.split("do()");
+	return R.sum(
+		parts.map((part) => {
+			const [toDo] = part.split("don't()");
+			return day3(toDo);
+		}),
+	);
+}