main.go

package main

import (
	"github.com/danvolchek/AdventOfCode/lib"
	"regexp"
)

type card struct {
	num     int
	winners lib.Set[int]
	yours   []int
}

func (c card) numWinners() int {
	return len(lib.Filter(c.yours, c.winners.Contains))
}

func (c card) totalCards(cards []card, memo map[int]int) int {
	if result, ok := memo[c.num]; ok {
		return result
	}

	numWinners := c.numWinners()

	cardsWon := numWinners

	for i := c.num; i < len(cards) && i < c.num+numWinners; i++ {
		cardsWon += cards[i].totalCards(cards, memo)
	}

	memo[c.num] = cardsWon
	return cardsWon
}

var cardRegexp = regexp.MustCompile(`Card *(\d+): ([^|]*) \| (.*)`)

func parse(match []string) card {
	return card{
		num:     lib.Atoi(match[0]),
		winners: lib.NewSet(lib.Ints(match[1])),
		yours:   lib.Ints(match[2]),
	}
}

func solve(cards []card) int {
	memo := make(map[int]int)
	totalCards := len(cards)

	for i := len(cards) - 1; i >= 0; i-- {
		totalCards += cards[i].totalCards(cards, memo)
	}

	return totalCards
}

func main() {
	solver := lib.Solver[[]card, int]{
		ParseF: lib.ParseLine(lib.ParseRegexp(cardRegexp, parse)),
		SolveF: solve,
	}

	solver.Expect("Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53\nCard 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19\nCard 3:  1 21 53 59 44 | 69 82 63 72 16 21 14  1\nCard 4: 41 92 73 84 69 | 59 84 76 51 58  5 54 83\nCard 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36\nCard 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11", 30)
	solver.Verify(9425061)
}