2022 day 13

Author: FriendlyUser1

2022/day13/distress.js

@@ -0,0 +1,60 @@
+const pairs = require("fs").readFileSync(`./input.txt`, "utf-8").split("\n\n"),
+	num = Number.isFinite,
+	compare = (l, r) => {
+		if (num(l) && num(r)) {
+			if (l < r) return 1;
+			if (l > r) return -1;
+		} else if (num(l)) return compare([l], r);
+		else if (num(r)) return compare(l, [r]);
+		else {
+			if (l === undefined) return 1;
+			else if (r === undefined) return -1;
+
+			for (let i = 0; i < Math.max(l.length, r.length); i++) {
+				let comp = compare(l[i], r[i], i);
+				if (comp !== 0) return comp;
+			}
+
+			if (l.length < r.length) return 1;
+			if (l.length > r.length) return -1;
+		}
+
+		return 0;
+	};
+
+let inOrder = 0;
+
+for (let j = 0; j < pairs.length; j++) {
+	let pair = pairs[j].split("\n");
+
+	let packet1 = JSON.parse(pair[0]),
+		packet2 = JSON.parse(pair[1]),
+		maxlen = Math.max(packet1.length, packet2.length);
+
+	if (maxlen < 1) inOrder += j + 1;
+
+	for (let i = 0; i < maxlen; i++) {
+		let left = packet1[i],
+			right = packet2[i],
+			ordered = compare(left, right);
+
+		if (ordered > 0) inOrder += j + 1;
+		if (ordered !== 0) break;
+		if (i === maxlen - 1) inOrder += j + 1;
+	}
+}
+
+console.log(`Sum of indices of pairs in order: ${inOrder}`); // Part 1
+
+// Part 2
+const packets = pairs.flatMap((p) => p.split("\n")).concat(["[[2]]", "[[6]]"]);
+
+let divider1 = 1,
+	divider2 = 1;
+
+for (let i = 0; i < packets.length; i++) {
+	if (compare(JSON.parse(packets[i]), [[2]]) === 1) divider1++;
+	if (compare(JSON.parse(packets[i]), [[6]]) === 1) divider2++;
+}
+
+console.log(`Decoder key: ${divider1 * divider2}`);