2023 Day 4 Complete!

2023/day04/main.go

@@ -0,0 +1,104 @@
+package main
+
+import (
+	"fmt"
+	"math"
+	"strings"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToStringSlice()
+	part1(inp)
+	fmt.Println()
+	part2(inp)
+}
+
+func part1(input []string) {
+	var total int
+	for i := range input {
+		total += cardFromLine(input[i]).Value()
+	}
+	fmt.Println("# Part 1")
+	fmt.Println(total)
+}
+
+func part2(input []string) {
+	cards := make(map[int]*Card)
+	for i := range input {
+		c := cardFromLine(input[i])
+		cards[c.id] = c
+	}
+	result := len(cards)
+	for _, card := range cards {
+		result += card.TotalCardsWon(cards)
+	}
+
+	fmt.Println("# Part 2")
+	fmt.Println(result)
+}
+
+type Card struct {
+	id      int
+	winners []int
+	numbers []int
+
+	winsCards     []int
+	totalCardsWon int
+}
+
+func (c Card) String() string {
+	return fmt.Sprintf("Card %d: %v | %v", c.id, c.winners, c.numbers)
+}
+
+func cardFromLine(input string) *Card {
+	pts := strings.Fields(input)
+	ret := Card{id: h.Atoi(pts[1]), totalCardsWon: -1}
+	winners := true
+	for _, s := range pts[2:] {
+		if s == "|" {
+			winners = false
+		} else {
+			if winners {
+				ret.winners = append(ret.winners, h.Atoi(s))
+			} else {
+				ret.numbers = append(ret.numbers, h.Atoi(s))
+			}
+		}
+	}
+	for _, w := range ret.winners {
+		for _, n := range ret.numbers {
+			skip := h.IntSliceContains(ret.winsCards, w)
+			if n == w && !skip {
+				ret.winsCards = append(ret.winsCards, w)
+			}
+			if skip {
+				break
+			}
+		}
+	}
+
+	return &ret
+}
+
+func (c *Card) Value() int {
+	return int(math.Pow(2, float64(len(c.winsCards)-1)))
+}
+
+func (c *Card) TotalCardsWon(cm map[int]*Card) int {
+	if c.totalCardsWon != -1 {
+		return c.totalCardsWon
+	}
+	result := len(c.winsCards)
+	// TODO: It doesn't with cards that match the ID,
+	// it wins X cards increasing from the current cards ID
+	// where x is the number of winning numbers matched
+	for i := 1; i <= len(c.winsCards); i++ {
+		if v, ok := cm[c.id+i]; ok {
+			result += v.TotalCardsWon(cm)
+		}
+	}
+	c.totalCardsWon = result
+	return result
+}