2024 day 13

2024/day-13/day13.ts

@@ -0,0 +1,69 @@
+const TOKENS_PER_PUSH_A = 3;
+const TOKENS_PER_PUSH_B = 1;
+
+export function part1(input: string) {
+	const configs = parseInput(input);
+	return solve(configs);
+}
+
+export function part2(input: string) {
+	const configs = parseInput(input).map((o) => {
+		return {
+			...o,
+			prize: o.prize.map((x) => x + 10000000000000),
+		};
+	});
+	return solve(configs);
+}
+
+function solve(parsed: ReturnType<typeof parseInput>) {
+	let final = 0;
+	parsed.forEach((config) => {
+		const options = findOptions(config);
+		if (options.length === 0) {
+			return;
+		}
+		final += options[0] * TOKENS_PER_PUSH_A + options[1] * TOKENS_PER_PUSH_B;
+	});
+	return final;
+}
+
+function findOptions(config: ReturnType<typeof parseInput>[number]) {
+	const [ax, ay] = config.buttonA;
+	const [bx, by] = config.buttonB;
+	const [gx, gy] = config.prize;
+	const ca = (gx * by - gy * bx) / (ax * by - ay * bx);
+	if (!isInt(ca)) return [];
+	return [ca, (gx - ca * ax) / bx];
+}
+
+function parseInput(input: string) {
+	const parts = input.split("\n\n");
+
+	return parts.map((part) => {
+		const [partA, partB, partResult] = part.split("\n");
+		const buttonA = partA
+			.replace("Button A: ", "")
+			.replace("X+", "")
+			.replace(" Y+", "")
+			.split(",")
+			.map(Number);
+		const buttonB = partB
+			.replace("Button B: ", "")
+			.replace("X+", "")
+			.replace(" Y+", "")
+			.split(",")
+			.map(Number);
+		const prize = partResult
+			.replace("Prize: ", "")
+			.replace("X=", "")
+			.replace(" Y=", "")
+			.split(",")
+			.map(Number);
+		return { buttonA, buttonB, prize };
+	});
+}
+
+function isInt(number: number) {
+	return number % 1 === 0;
+}