aoc21_6.js

import { timeStamp } from 'console';
import { accessSync, promises as fs } from 'fs';

(async()=>{
    const input = await fs.readFile("./interpretertests/aoc_21_6_input.txt", 'utf8')


    const f = (days) => {
        const timers = input.split(',').map(Number)
        let days8 = timers.map(t=>[1, t])
        const timersLen = timers.length

        for(let i = 0; i<days; i++){ 
            const days8Len = days8.length

            for(let j=0;j<days8Len;j++) {
                if (days8[j]) {
                    days8[j][1]--
                    if (days8[j][1]<0) {
                        days8[j][1] = 6
                        if (days8[i+timersLen]) days8[i+timersLen][0]+=days8[j][0]; else days8[i+timersLen] = [days8[j][0], 8]
                    }
                }
            }
        }
        return days8.reduce((acc, cur)=> acc+cur[0], 0)
    }
    console.log('part 1', f(80))
    console.log('part 2', f(256))

    // improvement after submit
    const f1 = (days) => {
        let fish = Array.apply(null, Array(9)).map(()=>0)
        input.split(',').map(Number).forEach(a => fish[a]++);

        for(let i = 0; i<days; i++){
            const newFish = fish.shift()
            fish[6] += newFish
            fish.push(newFish)
        }
        return fish.reduce((acc, cur)=> acc+cur, 0)
    }
  
    console.log('part 1', f1(80))
    console.log('part 2', f1(256))
    
    // wanted to remove remove the ugly (imho) array rotate and lack thereof in js
    const f2 = (days) => {
        let fish = Array.apply(null, Array(9)).map(()=>0)
        input.split(',').map(Number).forEach(a => fish[a]++);

        [...Array(days)].map((_, i) => fish[(i+7)%9] += fish[i%9])
        
        return fish.reduce((acc, cur)=> acc+cur, 0)
    }
  
    console.log('part 1', f2(80))
    console.log('part 2', f2(256))
    
})()