aoc24/solutions/06.ts

import { solvables } from "../main.ts";

import type { Solvable } from "../solvable.ts";
import { readInput } from "../utils.ts";

type Direction = "up" | "right" | "down" | "left"

class DaySix implements Solvable {
    input: string[][] = readInput('06').split('\n').map(col => col.split(''))
    map = this.input
    visitedLoc: Map<[number, number], null> = new Map()

    // assigned in part1
    startingPosition: [number, number] = [0, 0]

    turnRight = (direction: Direction): Direction => {
        switch (direction) {
            case 'up':
                return 'right'
            case 'right':
                return 'down'
            case 'down':
                return 'left'
            case 'left':
                return 'up'
        }
    }

    lookAhead = (x: number, y: number, direction: Direction): [number, number] => {
        switch (direction) {
            case 'up':
                return [x, y - 1]
            case 'down':
                return [x, y + 1]
            case 'right':
                return [x + 1, y]
            case 'left':
                return [x - 1, y]
        }
    }

    // returns true if out of bounds
    walk = (x: number, y: number, direction: Direction): [boolean, number, number, Direction] => {
        const nextStepInBounds = {
            up: y > 1,
            down: y < this.map.length,
            left: x > 1,
            right: x < this.map[0].length,
        }

        // if oob, return true
        if (!nextStepInBounds[direction]) {
            console.log('went oob')
            return [true, x, y, direction]
        } else {
            console.log(y, x, direction)
            // if obstacle ahead, return false and current location
            const [nextX, nextY] = this.lookAhead(x, y, direction)
            if (this.map[nextY][nextX] === '#') {
                return [false, x, y, this.turnRight(direction)]
            }
            // if no obstacle ahead, return false and new location
            return [false, nextX, nextY, direction]
        }
    }

    // path [y, x][]
    visualizePath = (path: [number, number][]): string => {
        const [height, width] = [this.map.length, this.map[0].length]
        const screenMat: string[][] = new Array(width).fill(new Array(height).fill('.'))
        for (const [y, x] of path) screenMat[y][x] = 'X'
        const screen: string = screenMat.map((line: string[]) => line.join('')).join('\n')
        return screen
    }

    public part1(): Solvable {
        // find starting position
        this.input.forEach((line, y) => line.forEach((char, x) => { if (char === '^') this.startingPosition = [y, x] }))
        let [x, y] = [this.startingPosition[0], this.startingPosition[1]]
        let direction: Direction = 'up'
        let outOfBounds = false

        while (!outOfBounds) {
            [outOfBounds, x, y, direction] = this.walk(x, y, direction)
            this.visitedLoc.set([y, x], null)
        }

        const path = this.visitedLoc.keys().toArray()
        const result: number = path.length
        console.log(this.visualizePath(path))
        console.log(path)
        console.log(result)

        return this
    }

    public part2(): Solvable {
        console.log()
        return this
    }
}

solvables.push(new DaySix())