AoC 2024 day 8

const fs = require("fs")

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

function parseInput(rawInput) {
    const map = rawInput.split(/\r?\n/)
    antennas = []
    width = map[0].length
    height = map.length

    map.forEach((row, y) => {
        row.split("").forEach((char, x) => {
            if (char !== ".") antennas.push({ x, y, freq: char })
        })
    })
}

function calculateAntinodes(includeBetween = false) {
    const antinodes = new Set()

    for (const group of Object.values(groups)) {
        group.forEach(({ x, y }) => antinodes.add(`${x},${y}`))

        for (let i = 0; i < group.length; i++) {
            for (let j = i + 1; j < group.length; j++) {
                const { x: x1, y: y1 } = group[i]
                const { x: x2, y: y2 } = group[j]
                const dx = x2 - x1,
                    dy = y2 - y1

                for (const dir of [-1, 1]) {
                    let x = x1 + dir * dx
                    let y = y1 + dir * dy

                    while (x >= 0 && x < width && y >= 0 && y < height) {
                        antinodes.add(`${x},${y}`)
                        if (!includeBetween) break
                        x += dir * dx
                        y += dir * dy
                    }
                }
            }
        }
    }

    return antinodes.size
}
let groups
function part1() {
    parseInput(input)

    groups = antennas.reduce((acc, ant) => {
        ;(acc[ant.freq] ||= []).push(ant)
        return acc
    }, {})

    return calculateAntinodes(false)
}

function part2() {
    return calculateAntinodes(true)
}

console.time("Part 1 Time")
console.log("Part 1:", part1())
console.timeEnd("Part 1 Time")

console.time("Part 2 Time")
console.log("Part 2:", part2())
console.timeEnd("Part 2 Time")