AoC 2024 day 1

// Advent of Code 2024 - Day 1
const fs = require("fs")

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

// Parse input
const parseInput = (rawInput) => rawInput.split("\n").map((line) => line.split("   ").map(Number))

// Part 1: Calculate total absolute difference
const part1 = (data) => {
    const [left, right] = [
        data.map((row) => row[0]).sort((a, b) => a - b),
        data.map((row) => row[1]).sort((a, b) => a - b)
    ]

    return left.reduce((sum, value, index) => sum + Math.abs(value - right[index]), 0)
}

// Part 2: Calculate weighted total using occurrences
const part2 = (data) => {
    const left = data.map((row) => row[0])
    const rightOccurrences = data.reduce((map, val) => map.set(val[1], (map.get(val[1]) || 0) + 1), new Map())

    return left.reduce((sum, val) => sum + val * (rightOccurrences.get(val) || 0), 0)
}

// Run both parts
const data = parseInput(input)

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

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