Golang solution to AOC21 day6

main.go

package main

import (
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
)

func main() {
	/*
		Loading and formatting data
	*/
	content, err := os.ReadFile("input.txt")
	if err != nil {
		log.Fatal(err)
	}

	s := string(content)
	aux := strings.FieldsFunc(s, func(r rune) bool { return strings.ContainsRune(" ,\n", r) })

	var fish []int
	for _, v := range aux {
		n, err := strconv.Atoi(v)
		if err != nil {
			log.Fatal(err)
		}
		fish = append(fish, n)
	}

	/*
		Main loop of the slice of fish.
		Calling a recursive function with memoization (caching)
	*/
	var res uint64 = 0
	comp := newMemoizedCompute()
	for _, v := range fish {
		res += comp(256, v)
	}
	fmt.Println("Final number of fish:", res)
}

func newMemoizedCompute() func(int, int) uint64 {
	type key struct {
		ttl  int // Time to Live: when 0 no more processing
		load int // Internal timer: before spanning new fish
	}
	cache := make(map[key]uint64)
	var fn func(int, int) uint64
	fn = func(ttl int, load int) uint64 {
		ttl = ttl - (load + 1)
		if ttl < 0 {
			return 1
		}
		if _, ok := cache[key{ttl, load}]; !ok {
			cache[key{ttl, load}] = fn(ttl, 6) + fn(ttl, 8)
		}
		return cache[key{ttl, load}]
	}
	return fn
}