day3 and 4

2023/go/day04/day04.go

@@ -0,0 +1,98 @@
+package day04
+
+import (
+	"math"
+	"regexp"
+	"strings"
+
+	"fmt"
+
+	"adventofcode2023/utils"
+
+	mapset "github.com/deckarep/golang-set/v2"
+)
+
+type Game struct {
+	ID      int
+	matches int
+	count  int
+	winners mapset.Set[int]
+	cards mapset.Set[int]
+}
+
+func Part1(input string) int {
+	games, err := parseGames(input)
+	if err != nil {
+		fmt.Println("Error:", err)
+		return -1
+	}
+
+	points := 0.0
+	for _, game := range games {
+		matches := len(game.cards.Intersect(game.winners).ToSlice())
+		if matches > 0 {
+			points += math.Pow(2, float64(matches - 1))
+		}
+	}
+	return int(points)
+}
+
+func Part2(input string) int {
+	games, err := parseGames(input)
+	if err != nil {
+		fmt.Println("Error:", err)
+		return -1
+	}
+
+	for i, game := range games {
+		matches := game.cards.Intersect(game.winners).ToSlice()
+		games[i].matches = len(matches)
+		games[i].count = 1
+	}
+
+	for i:=0;i<len(games);i++{
+		for j:=0;j<games[i].count;j++ {
+			for k:=1;k<=games[i].matches;k++ {
+				games[i+k].count++
+			}
+		}
+	}
+	
+	cards := 0
+	for i:=0;i<len(games);i++{
+		cards += games[i].count
+	}
+	return cards
+}
+
+func parseGames(input string) ([]Game, error) {
+	
+	var game Game
+	var games []Game
+
+	lines := strings.Split(input, "\n")
+	for _, line := range lines {
+		reID := regexp.MustCompile(`Card\s*(\d+):(.*) \| (.*)`)
+		match := reID.FindStringSubmatch(line)
+		if len(match) != 4 {
+			return games, fmt.Errorf("unable to extract game")
+		}
+
+		game.ID = utils.MustAtoi(match[1])
+		game.winners = getNumbers(match[2])
+		game.cards = getNumbers(match[3])
+
+		games = append(games, game)
+	}
+	return games, nil
+}
+
+func getNumbers(input string) mapset.Set[int] {
+	tokens := strings.Fields(input)
+	var numbers []int
+	for _, token := range tokens {
+		num := utils.MustAtoi(token)
+		numbers = append(numbers, num)
+	}
+	return mapset.NewSet[int](numbers...)
+}