Advent of Code 2021 Day 6

6a.go

package main

import (
	_ "embed"
	"fmt"
	"strconv"
	"strings"
)

//go:embed input.txt
var input string

func main() {
	nums := strings.Split(input, ",")
	vals := make([]int, len(nums))
	var err error
	for i, num := range nums {
		vals[i], err = strconv.Atoi(num)
		if err != nil {
			panic(err)
		}
	}

	// Age
	for i := 0; i < 80; i++ {
		for i := range vals {
			vals[i]--
			if vals[i] == -1 {
				vals = append(vals, 8)
				vals[i] = 6
			}
		}
	}

	fmt.Println(len(vals))
}

6b.go

package main

import (
	_ "embed"
	"fmt"
	"strconv"
	"strings"
)

//go:embed input.txt
var input string

func main() {
	nums := strings.Split(input, ",")
	buckets := make(map[int]int)
	for _, num := range nums {
		v, err := strconv.Atoi(num)
		if err != nil {
			panic(err)
		}
		buckets[v]++
	}

	// Age
	for i := 0; i < 256; i++ {
		newBuckets := make(map[int]int)
		for k, v := range buckets {
			if k-1 < 0 {
				newBuckets[8] += v
				newBuckets[6] += v
			} else {
				newBuckets[k-1] += v
			}
		}
		buckets = newBuckets
	}

	out := 0
	for _, v := range buckets {
		out += v
	}
	fmt.Println(out)
}