AoC 2024 day 2

// Advent of Code 2024 - Day 2
const fs = require("fs")

const input = fs.readFileSync(__dirname + (process.argv.includes("--test") ? "/test.txt" : "/input.txt"), "utf8").trim()
const data = input.split("\n").map((r) => r.split(" ").map(Number))

// Check if a report is safe
const isReportSafe = (report) => {
    const diffs = report.slice(1).map((level, i) => level - report[i])
    const isIncreasing = diffs[0] > 0

    return diffs.every((diff) => Math.abs(diff) >= 1 && Math.abs(diff) <= 3 && diff > 0 === isIncreasing)
}

// Check if removing one level makes the report safe
const isSafeWithOneRemoval = (report) =>
    report.some((_, i) => isReportSafe(report.slice(0, i).concat(report.slice(i + 1))))

// Part 1: Count reports that are directly safe
const part1 = (data) => data.filter(isReportSafe).length

// Part 2: Count reports that are safe or can be made safe by removing one level
const part2 = (data) => data.filter((report) => isReportSafe(report) || isSafeWithOneRemoval(report)).length

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")