2024 day 14

Author: FriendlyUser1

2024/day14/robots.js

@@ -0,0 +1,104 @@
+const inputs = require("fs").readFileSync("./input.txt", "utf-8").split("\n");
+const mod = (n1, n2) => ((n1 % n2) + n2) % n2;
+
+const WIDTH = 101,
+	HEIGHT = 103,
+	HALFWIDTH = 50,
+	HALFHEIGHT = 51;
+
+class Robot {
+	/** @type {number} x */ x;
+	/** @type {number} x */ y;
+	/** @type {number} x */ velX;
+	/** @type {number} x */ velY;
+
+	constructor(x, y, velX, velY) {
+		this.x = x;
+		this.y = y;
+		this.velX = velX;
+		this.velY = velY;
+	}
+
+	move() {
+		this.y = mod(this.y + this.velY, HEIGHT);
+		this.x = mod(this.x + this.velX, WIDTH);
+
+		return this;
+	}
+
+	get quad() {
+		let [x, y, HW, HH] = [this.x, this.y, HALFWIDTH, HALFHEIGHT];
+
+		return x == HW || y == HH ? 4 : x < HW ? (y < HH ? 0 : 2) : y < HH ? 1 : 3;
+	}
+}
+
+/** @returns {Set<Robot>} */
+const getRobots = () => {
+	const robots = new Set();
+
+	for (const input of inputs.values()) {
+		const matches = [...input.matchAll(/-?\d+,-?\d+/g)].map((match) =>
+			match[0].split(",").map((n) => parseInt(n))
+		);
+		let robot = new Robot(...matches.flat());
+		robots.add(robot);
+	}
+
+	return robots;
+};
+
+const checkSafety = (seconds) => {
+	const robots = getRobots();
+
+	for (let _ = 0; _ < 100; _++) robots.forEach((robot) => robot.move());
+
+	let quads = [0, 0, 0, 0];
+	robots.forEach((robot) => {
+		if (robot.quad < 4) quads[robot.quad]++;
+	});
+
+	const safetyFactor = quads.reduce((acc, quad) => quad * acc);
+
+	return `Safety factor after ${seconds} seconds: ${safetyFactor}`;
+};
+
+const findTree = (char) => {
+	const robots = getRobots();
+	let foundTree = false,
+		visual = [],
+		sec = 0;
+
+	const isTree = (row) => new RegExp(`${char}{31}`).test(row.join(""));
+
+	while (!foundTree) {
+		visual = [];
+
+		robots.forEach((robot) => robot.move());
+		sec++;
+
+		for (let _ = 0; _ < HEIGHT; _++) visual.push(" ".repeat(WIDTH).split(""));
+
+		for (const robot of robots.values())
+			if (visual[robot.y][robot.x] == " ") visual[robot.y][robot.x] = char;
+
+		foundTree = visual.some(isTree);
+	}
+
+	let treeStart = visual.findIndex(isTree),
+		treeEnd = visual.findLastIndex(isTree);
+
+	console.log("\n[...]");
+	console.log(
+		visual
+			.slice(treeStart, treeEnd + 1)
+			.map((row) => row.join(""))
+			.join("\n")
+	);
+	console.log("[...]\n");
+
+	return `Found tree at ${sec} seconds.`;
+};
+
+console.log(checkSafety(100));
+console.log(findTree("X"));