AoC 2024 day 10

const fs = require("fs")

const input = fs.readFileSync(__dirname + (process.argv.includes("--test") ? "/test.txt" : "/input.txt"), "utf8")

const map = input
    .trim()
    .split(/\r?\n/)
    .map((row) => row.split("").map(Number))

const numRows = map.length
const numCols = map[0].length

const directions = [
    [0, 1],
    [0, -1],
    [1, 0],
    [-1, 0]
]

const isValidMove = (map, x, y, currentHeight) =>
    x >= 0 && x < map.length && y >= 0 && y < map[0].length && map[x][y] === currentHeight + 1

const traverse = (map, func) => {
    let sum = 0
    for (let i = 0; i < numRows; i++) {
        for (let j = 0; j < numCols; j++) {
            if (map[i][j] === 0) {
                sum += func(i, j)
            }
        }
    }
    return sum
}

const findTrails = (x, y, visited) => {
    visited ||= new Set()

    const key = `${x},${y}`
    if (visited.has(key)) return 0
    visited.add(key)

    if (map[x][y] === 9) return 1

    let score = 0
    for (const [dx, dy] of directions) {
        const newX = x + dx,
            newY = y + dy
        if (isValidMove(map, newX, newY, map[x][y]) && !visited.has(`${newX},${newY}`)) {
            score += findTrails(newX, newY, visited)
        }
    }

    return score
}

const countTrails = (x, y) => {
    if (map[x][y] === 9) return 1

    let count = 0
    for (const [dx, dy] of directions) {
        const newX = x + dx,
            newY = y + dy
        if (isValidMove(map, newX, newY, map[x][y])) {
            count += countTrails(newX, newY)
        }
    }

    return count
}

console.time("Part 1 Time")
console.log("Part 1:", traverse(map, findTrails))
console.timeEnd("Part 1 Time")

console.time("Part 2 Time")
console.log("Part 2:", traverse(map, countTrails))
console.timeEnd("Part 2 Time")