day 5

day-5/day5.ts

@@ -0,0 +1,89 @@
+export function day5(input: string) {
+	let result = 0;
+
+	const [rulesStr, updatesStr] = input.split("\n\n");
+
+	const rules = rulesStr.split("\n").map((x) => x.split("|"));
+	const updates = updatesStr.split("\n").map((x) => x.split(","));
+
+	for (const update of updates) {
+		let isValid = true;
+		for (let i = 0; i < rules.length; i++) {
+			const rule = rules[i];
+			const x = rule[0];
+			const y = rule[1];
+			const xIndex = update.indexOf(x);
+			const yIndex = update.indexOf(y);
+			if (xIndex === -1 || yIndex === -1) {
+				continue;
+			}
+			if (yIndex < xIndex) {
+				console.log("not valid", {
+					x,
+					y,
+					xIndex,
+					yIndex,
+					update,
+				});
+				isValid = false;
+				break;
+			}
+		}
+
+		if (isValid) {
+			const middleValue = update[Math.floor(update.length / 2)];
+			result += Number.parseInt(middleValue);
+		}
+	}
+
+	return result;
+}
+
+export function day5part2(input: string) {
+	let result = 0;
+
+	const [rulesStr, updatesStr] = input.split("\n\n");
+
+	const rules = rulesStr.split("\n").map((x) => x.split("|"));
+	const updates = updatesStr.split("\n").map((x) => x.split(","));
+
+	const invalidUpdates = [];
+	for (const update of updates) {
+		let isValid = true;
+		for (let i = 0; i < rules.length; i++) {
+			const rule = rules[i];
+			const x = rule[0];
+			const y = rule[1];
+			const xIndex = update.indexOf(x);
+			const yIndex = update.indexOf(y);
+			if (xIndex === -1 || yIndex === -1) {
+				continue;
+			}
+			if (yIndex < xIndex) {
+				isValid = false;
+				break;
+			}
+		}
+
+		if (!isValid) {
+			invalidUpdates.push(update);
+		}
+	}
+
+	for (const update of invalidUpdates) {
+		update.sort((a, b) => {
+			const rule = rules.find((v) => v.includes(a) && v.includes(b));
+			if (!rule) {
+				return 0;
+			}
+			if (rule[0] === a) {
+				return -1;
+			}
+			return 1;
+		});
+		const middleValue = update[Math.floor(update.length / 2)];
+		result += Number.parseInt(middleValue);
+	}
+
+	return result;
+}