readme.md

This is my node.js solution to https://adventofcode.com/2018/day/12

aoc-day-12.js

#!/usr/bin/env node

const numberOfGenerations = 20
const initialGenerationOfPots = '#..#.#..##......###...###'.split('')
const rules = [
  '...##',
  '..#..',
  '.#...',
  '.#.#.',
  '.#.##',
  '.##..',
  '.####',
  '#.#.#',
  '#.###',
  '##.#.',
  '##.##',
  '###..',
  '###.#',
  '####.'
]

const FULL = '#'
const EMPTY = '.'

function bitmap(acc, char, idx) {
  return acc | ((char === FULL) ? 2**idx : 0)
}

const bitmappedRules = rules.map(rule => rule.split('').reverse().reduce(bitmap, 0))

const finalGenerationOfPots = Array(numberOfGenerations).fill(0).reduce((currentGenerationOfPots, _, idx) => {
  console.log(`generation ${idx}: ${currentGenerationOfPots.join('')}`)

  const bitmappedPots = []

  currentGenerationOfPots.concat(Array.from('....')).reduce((currentSlice, pot) => {
    currentSlice.push(pot)
    bitmappedPots.push(currentSlice.slice(0, 5).reverse().reduce(bitmap, 0))
    return currentSlice.slice(1, 5)
  }, Array.from('....'))

  return bitmappedPots.map(bitmappedPot => bitmappedRules.includes(bitmappedPot) ? FULL : EMPTY)
}, initialGenerationOfPots)

const count = finalGenerationOfPots.reduce((count, currentPot, idx) => {
  return (currentPot === FULL) ? count + idx - numberOfGenerations*2 : count
}, 0)

console.log(`count: ${count}`)

package.json

{ 
  "name": "aoc-day-12", 
  "version": "0.0.0", 
  "bin": "./aoc-day-12.js" 
}