part1.ts

import * as fs from 'fs';
import type { Point } from '../../types';

const input = fs.readFileSync('input', 'utf8');

type Stream = { input: string; index: number };

const rocks = 2022;

const shapes = [
	['####'],
	['.#.', '###', '.#.'],
	['..#', '..#', '###'],
	['#', '#', '#', '#'],
	['##', '##'],
].map((shape) => {
	const cells: Point[] = [];
	for (let y = 0; y < shape.length; y++) {
		for (let x = 0; x < shape[y].length; x++) {
			if (shape[y][x] === '#') {
				cells.push({ x, y } as Point);
			}
		}
	}
	return { cells, shapeHeight: shape.length };
});
const stream: Stream = { input, index: 0 };
const cave: string[][] = [];

const drop = (cave: string[][], cells: Point[], stream: Stream) => {
	const pos: Point = { x: 2, y: 0 };
	let settled = false;
	while (!settled) {
		const direction = stream.input[stream.index++ % stream.input.length];
		move(cave, pos, cells, { x: direction === '<' ? -1 : 1, y: 0 } as Point);
		if (!move(cave, pos, cells, { x: 0, y: 1 } as Point)) {
			cells.forEach((cell) => (cave[pos.y + cell.y][pos.x + cell.x] = '#'));
			settled = true;
		}
	}
	return pos.y;
};
const move = (cave: string[][], pos: Point, cells: Point[], offset: Point) => {
	const next = { x: pos.x + offset.x, y: pos.y + offset.y };
	if (cells.every((cell) => cave[next.y + cell.y]?.[next.x + cell.x] === '.')) {
		pos.x += offset.x;
		pos.y += offset.y;
		return true;
	}
	return false;
};

let depth = 0;
let height = 0;

for (let i = 0; i < rocks; i++) {
	const { cells, shapeHeight } = shapes[i % shapes.length];
	while (depth < height + shapeHeight + 3) {
		cave.unshift(new Array(7).fill('.'));
		depth++;
	}
	while (depth > height + shapeHeight + 3) {
		cave.shift();
		depth--;
	}
	const y = drop(cave, cells, stream);
	height = Math.max(height, depth - y);
}

console.log(height);