AoC 2023 day 10

const fs = require("fs")
const performance = require("perf_hooks").performance
const eol = require("os").EOL

let startTime = performance.now()
let part1 = 0
let part2 = 0
let input = fs.readFileSync(__dirname + "/data.txt", "utf8").split(eol)

let pos
let map = input.map((val, i) => {
    let row = val.split("")
    let sPos = row.indexOf("S")
    if (sPos > -1) {
        pos = { x: sPos, y: i }
        row[sPos] = "J" // My startNode, might be different for other maps
    }
    return row
})

const topN = "|JL"
const leftN = "-7J"
const bottomN = "|7F"
const rightN = "-LF"

const visited = new Set()

function getNext(pos) {
    let type = map[pos.y][pos.x]
    if (topN.includes(type) && !visited.has(`${pos.x}-${pos.y - 1}`)) return { x: pos.x, y: pos.y - 1 }
    if (leftN.includes(type) && !visited.has(`${pos.x - 1}-${pos.y}`)) return { x: pos.x - 1, y: pos.y }
    if (bottomN.includes(type) && !visited.has(`${pos.x}-${pos.y + 1}`)) return { x: pos.x, y: pos.y + 1 }
    if (rightN.includes(type) && !visited.has(`${pos.x + 1}-${pos.y}`)) return { x: pos.x + 1, y: pos.y }
}

while (true) {
    visited.add(`${pos.x}-${pos.y}`)
    pos = getNext(pos)
    if (pos == undefined) break
}

part1 = visited.size / 2

function countCrossings(inputString) {
    const matches = inputString.match(/\||L7|FJ/g)
    return matches ? matches.length : 0
}

map.forEach((row, y) => {
    let rowM = ""
    row.forEach((element, x) => {
        let poly = visited.has(`${x}-${y}`)
        if (poly && element != "-") rowM += element
        if (!poly && countCrossings(rowM) & 1) part2++
    })
})

let endTime = performance.now() - startTime
console.log(`Part 1: ${part1}\nPart 2: ${part2}\nTimer: ${endTime} ms`)