2022-17 in js

2022/17-Pyroclastic-Flow/first.js

@@ -0,0 +1,164 @@
+import * as fs from "fs";
+
+function load(filename) {
+	let data = fs.readFileSync(filename, "utf8").trim();
+	const l = data.length;
+	let i = 0;
+	return {
+		next: function () {
+			const c = data[i];
+			i = (i + 1) % l;
+			return c;
+		}
+	};
+}
+
+const shapes = [
+	[0b0011110],
+	[0b0001000, 0b0011100, 0b0001000],
+	[0b0000100, 0b0000100, 0b0011100],
+	[0b0010000, 0b0010000, 0b0010000, 0b0010000],
+	[0b0011000, 0b0011000],
+];
+const shapes_len = shapes.length;
+
+class Shape {
+	constructor(shape) {
+		this.shape = shape;
+		this.length = shape.length;
+	}
+	fall(field) { // returns true if the shape fell without colliding
+		for (let i=0; i<this.length; ++i) {
+			const next = field.get(i+1);
+			if (next === undefined || next & this.shape[i]) { //collision
+				field.solidify(this.shape);
+				return false;
+			}
+		}
+		field.fall();
+		return true;
+	}
+	shift(field, direction) {
+		let collision = false;
+		let tmp;
+		switch(direction) {
+		case ">":
+			tmp = this.shape.map(line => {
+				if (line & 0b1) { // we touch the right edge already
+					collision = true;
+				}
+				return line >>> 1;
+			});
+			break;
+		case "<":
+			tmp = this.shape.map(line => {
+				if (line & 0b1000000) { // we touch the left edge already
+					collision = true;
+				}
+				return line << 1;
+			});
+			break;
+		default:
+			throw "invalid direction character in shape shift: " + direction;
+		}
+		if (collision) {
+			return;
+		}
+		for (let i=0; i<this.length; ++i) {
+			if (field.get(i) & tmp[i]) { //collision
+				return;
+			}
+		}
+		this.shape = tmp;
+	}
+	print() {
+		this.shape.forEach(line => {
+			console.log(
+				line & 0b1000000 ? "#" : ".",
+				line & 0b0100000 ? "#" : ".",
+				line & 0b0010000 ? "#" : ".",
+				line & 0b0001000 ? "#" : ".",
+				line & 0b0000100 ? "#" : ".",
+				line & 0b0000010 ? "#" : ".",
+				line & 0b0000001 ? "#" : ".",
+			);
+		});
+		console.log("=======");
+	}
+}
+class Shaper {
+	constructor() {
+		this.index = 0;
+	}
+	next(field) {
+		const s = new Shape(shapes[this.index]);
+		field.accomodate(shapes[this.index].length + 3);
+		this.index = (this.index + 1) % shapes_len;
+		return s;
+	}
+}
+class Field {
+	constructor() {
+		this.data = [];
+		this.offset = 0;
+	}
+	accomodate(n) {
+		this.offset = 0;
+		for(let i=0; i<n; ++i) {
+			this.data.unshift(0);
+		}
+	}
+	fall() {
+		if (this.data[0] !== 0) { // we need to fall bellow the top line?
+			this.offset++;
+		} else {
+			this.data.shift();
+		}
+	}
+	get(offset) {
+		return this.data[this.offset + offset];
+	}
+	print() {
+		this.data.forEach(line => {
+			console.log(
+				line & 0b1000000 ? "#" : ".",
+				line & 0b0100000 ? "#" : ".",
+				line & 0b0010000 ? "#" : ".",
+				line & 0b0001000 ? "#" : ".",
+				line & 0b0000100 ? "#" : ".",
+				line & 0b0000010 ? "#" : ".",
+				line & 0b0000001 ? "#" : ".",
+			);
+		});
+		console.log("-------");
+	}
+	solidify(shape) {
+		for(let i=0; i<shape.length; ++i) {
+			this.data[i+this.offset] |= shape[i];
+		}
+	}
+}
+
+let example = load("example");
+let input = load("input");
+
+function solve(input) {
+	let field = new Field();
+	let shaper = new Shaper();
+	for(let i=0; i<2022; ++i) {
+		let shape = shaper.next(field);
+		do {
+			shape.shift(field, input.next());
+		} while(shape.fall(field));
+	}
+	field.print();
+	return field.data.length;
+}
+
+const exampleOutput = solve(example);
+if (exampleOutput !== 3068) {
+	console.log("Example failed with height " + exampleOutput);
+	process.exit(1); // eslint-disable-line
+}
+
+console.log(solve(input));