2022-22 part 1 in js

2022/22-Monkey-Map/first.js

@@ -0,0 +1,144 @@
+import * as fs from 'fs';
+
+class Line {
+	constructor(line) {
+		this.x = 0;
+		for(let i=0; i<line.length; ++i) {
+			if (line[i] == ' ') ++this.x;
+		}
+		this.data = line.slice(this.x);
+	}
+}
+
+const RIGHT=0, DOWN=1, LEFT=2, UP=3;
+
+class Walker {
+	constructor(lines, algo) {
+		this.lines = lines;
+		this.x = lines[0].x;
+		this.y = 0;
+		this.algo = algo;
+		this.direction=RIGHT;
+		this.height = this.lines.length;
+	}
+	isIn(x, y) {
+		if (y >= 0 && y < this.height) {
+			const line = this.lines[y];
+			if (x >= line.x && x < line.x + line.data.length) {
+				return true;
+			}
+		}
+		return false;
+	}
+	step(d) {
+		for(; d>0; --d) {
+			let line;
+			switch(this.direction) {
+			case RIGHT:
+				line = this.lines[this.y];
+				if (this.isIn(this.x+1, this.y)) {
+					if (line.data[this.x+1-line.x] === '.') {
+						++this.x;
+					}
+				} else {
+					if (line.data[0] === '.') {
+						this.x = line.x;
+					}
+				}
+				break;
+			case LEFT:
+				line = this.lines[this.y];
+				if (this.isIn(this.x-1, this.y)) {
+					if (line.data[this.x-1-line.x] === '.') {
+						--this.x;
+					}
+				} else {
+					if (line.data[line.data.length - 1] === '.') {
+						this.x = line.x + line.data.length - 1;
+					}
+				}
+				break;
+			case DOWN:
+				if (this.isIn(this.x, this.y+1)) {
+					line = this.lines[this.y+1];
+					if (line.data[this.x-line.x] === '.') {
+						++this.y;
+					}
+				} else {
+					let y = this.y;
+					while (this.isIn(this.x, y - 1)) {
+						--y;
+					}
+					line = this.lines[y];
+					if (line.data[this.x - line.x] === '.') {
+						this.y = y;
+					}
+				}
+				break;
+			case UP:
+				if (this.isIn(this.x, this.y-1)) {
+					line = this.lines[this.y-1];
+					if (line.data[this.x-line.x] === '.') {
+						--this.y;
+					}
+				} else {
+					let y = this.y;
+					while (this.isIn(this.x, y + 1)) {
+						++y;
+					}
+					line = this.lines[y];
+					if (line.data[this.x - line.x] === '.') {
+						this.y = y;
+					}
+				}
+				break;
+			default: throw "unreachable";
+			}
+		}
+	}
+	walk() {
+		let d = 0;
+		for (let i=0; i<this.algo.length; ++i) {
+			const c = this.algo[i];
+			switch(c) {
+			case 'L':
+				this.step(d);
+				d = 0;
+				this.direction = (this.direction + 3) % 4;
+				break;
+			case 'R':
+				this.step(d);
+				d = 0;
+				this.direction = (this.direction +1) % 4;
+				break;
+			default:
+				d = d * 10 + parseInt(c);
+			}
+		}
+		this.step(d);
+		return 1000 * (this.y + 1) + 4 * (this.x + 1) + this.direction;
+	}
+}
+
+function load(filename) {
+	let lines = fs.readFileSync(filename, 'utf8').split('\n');
+	return new Walker(
+		lines.slice(0, -3).map(line => new Line(line)),
+		lines[lines.length - 2]
+	);
+}
+
+let example = load('example');
+let input = load('input');
+
+function solve(input) {
+	return input.walk();
+}
+
+const exampleOutput = solve(example);
+if (exampleOutput !== 6032) {
+	console.log('Example failed with ' + exampleOutput);
+	process.exit(1); // eslint-disable-line
+}
+
+console.log(solve(input));