2024 day 15

2024/day-15/day15.ts

@@ -0,0 +1,239 @@
+import { logLines } from "../../utils/log-lines.ts"
+const keypress = async () => {
+	process.stdin.setRawMode(true)
+	return new Promise((resolve) =>
+		process.stdin.once("data", (data) => {
+			const byteArray = [...data]
+			if (byteArray.length > 0 && byteArray[0] === 3) {
+				console.log("^C")
+				process.exit(1)
+			}
+			process.stdin.setRawMode(false)
+			resolve()
+		}),
+	)
+}
+enum Move {
+	Up = "^",
+	Down = "v",
+	Right = ">",
+	Left = "<",
+}
+
+enum Unit {
+	Box = "O",
+	Robot = "@",
+	Wall = "#",
+	Empty = ".",
+}
+
+type Grid = Unit[][]
+type Coordinates = [number, number]
+
+export async function part1(input: string) {
+	const { moves, grid } = parseInput(input)
+	let robotPosition = getRobotStartingPosition(grid)
+	for (const move of moves) {
+		try {
+			const emptySqCoords = canExecuteMove(robotPosition, grid, move)
+			robotPosition = await executeMove(grid, move, emptySqCoords)
+		} catch (e) {
+			// console.log("error", e.message)
+		}
+	}
+	logGrid(grid)
+	return getGPS(grid)
+}
+
+export function parseInput(input: string) {
+	const [gridStr, movesStr] = input.split("\n\n")
+	const moves = movesStr
+		.split("\n")
+		.join("")
+		.split("")
+		.map((move) => {
+			if (move === Move.Up) {
+				return Move.Up
+			}
+			if (move === Move.Down) {
+				return Move.Down
+			}
+			if (move === Move.Right) {
+				return Move.Right
+			}
+			if (move === Move.Left) {
+				return Move.Left
+			}
+			throw new Error(`Invalid input: ${move}`)
+		})
+
+	const grid = gridStr.split("\n").map((line) =>
+		line.split("").map((u) => {
+			if (u === Unit.Box) {
+				return Unit.Box
+			}
+			if (u === Unit.Empty) {
+				return Unit.Empty
+			}
+			if (u === Unit.Robot) {
+				return Unit.Robot
+			}
+			if (u === Unit.Wall) {
+				return Unit.Wall
+			}
+			throw new Error(`Invalid input unit: ${u}`)
+		}),
+	)
+	return { moves, grid }
+}
+
+export function getRobotStartingPosition(grid: Grid): Coordinates {
+	for (let i = 0; i < grid.length; i++) {
+		const line = grid[i]
+		for (let i1 = 0; i1 < line.length; i1++) {
+			const unit = line[i1]
+			if (unit === Unit.Robot) {
+				return [i, i1]
+			}
+		}
+	}
+	throw new Error("Robot not found")
+}
+
+export function canExecuteMove(
+	position: Coordinates,
+	grid: Grid,
+	move: Move,
+): Coordinates {
+	// console.log("CAN EXECUTE?: ")
+	// logGrid(grid)
+
+	const { unit: nextItem, coordinates: nextItemCoordinates } = getNextItem(
+		position,
+		grid,
+		move,
+	)
+
+	if (!nextItem) {
+		throw new Error("wtf")
+	}
+	if (nextItem === Unit.Wall) {
+		throw new Error("Wall found, can't execute move sequence.")
+	}
+	if (nextItem === Unit.Empty) {
+		return nextItemCoordinates
+	}
+	return canExecuteMove(nextItemCoordinates, grid, move)
+}
+
+export async function executeMove(
+	grid: Grid,
+	move: Move,
+	emptySquareCoordinates: Coordinates,
+): Promise<Coordinates> {
+	if (move === Move.Down) {
+		let currentCoordinates = emptySquareCoordinates
+		while (true) {
+			// console.log(move, currentCoordinates)
+			// logGrid(grid)
+			const [cr, cc] = currentCoordinates
+			const prevItem = grid[cr - 1][cc]
+			if (prevItem === Unit.Robot) {
+				grid[cr][cc] = Unit.Robot
+				grid[cr - 1][cc] = Unit.Empty
+				return [cr, cc]
+			}
+			grid[cr][cc] = prevItem
+			currentCoordinates = [cr - 1, cc]
+		}
+	}
+	if (move === Move.Up) {
+		let currentCoordinates = emptySquareCoordinates
+		while (true) {
+			// console.log(move, currentCoordinates)
+			// logGrid(grid)
+			const [cr, cc] = currentCoordinates
+			const prevItem = grid[cr + 1][cc]
+			if (prevItem === Unit.Robot) {
+				grid[cr][cc] = Unit.Robot
+				grid[cr + 1][cc] = Unit.Empty
+				return [cr, cc]
+			}
+			grid[cr][cc] = prevItem
+			currentCoordinates = [cr + 1, cc]
+		}
+	}
+	if (move === Move.Right) {
+		let currentCoordinates = emptySquareCoordinates
+		while (true) {
+			// await keypress()
+			// console.log(move, currentCoordinates)
+			// logGrid(grid)
+
+			const [cr, cc] = currentCoordinates
+			const prevItem = grid[cr][cc - 1]
+			if (prevItem === Unit.Robot) {
+				grid[cr][cc] = Unit.Robot
+				grid[cr][cc - 1] = Unit.Empty
+				return [cr, cc]
+			}
+			grid[cr][cc] = prevItem
+			currentCoordinates = [cr, cc - 1]
+		}
+	}
+	if (move === Move.Left) {
+		let currentCoordinates = emptySquareCoordinates
+		while (true) {
+			// await keypress()
+			// console.log(move, currentCoordinates)
+			// logGrid(grid)
+
+			const [cr, cc] = currentCoordinates
+			const prevItem = grid[cr][cc + 1]
+			if (prevItem === Unit.Robot) {
+				grid[cr][cc] = Unit.Robot
+				grid[cr][cc + 1] = Unit.Empty
+				return [cr, cc]
+			}
+			grid[cr][cc] = prevItem
+			currentCoordinates = [cr, cc + 1]
+		}
+	}
+	throw new Error("asdf")
+}
+
+function getNextItem([r, c]: Coordinates, grid: Grid, move: Move) {
+	let coordinates: Coordinates
+	if (move === Move.Left) {
+		coordinates = [r, c - 1]
+	} else if (move === Move.Right) {
+		coordinates = [r, c + 1]
+	} else if (move === Move.Up) {
+		coordinates = [r - 1, c]
+	} else if (move === Move.Down) {
+		coordinates = [r + 1, c]
+	} else {
+		throw new Error("Invalid input for getNextItem")
+	}
+
+	const unit = grid[coordinates[0]][coordinates[1]] as Unit | undefined
+	return { unit, coordinates }
+}
+
+function getGPS(grid: Grid) {
+	let GPS = 0
+	for (let i = 0; i < grid.length; i++) {
+		const line = grid[i]
+		for (let i1 = 0; i1 < line.length; i1++) {
+			const unit = line[i1]
+			if (unit === Unit.Box) {
+				GPS += i * 100 + i1
+			}
+		}
+	}
+	return GPS
+}
+
+function logGrid(grid: Grid) {
+	logLines(grid.map((x) => x.join("")))
+}