2023/go/day04/day04.go

   1 package day04
   2
   3 import (
   4         "math"
   5         "regexp"
   6         "strings"
   7
   8         "fmt"
   9
  10         "adventofcode2023/utils"
  11
  12         mapset "github.com/deckarep/golang-set/v2"
  13 )
  14
  15 type Game struct {
  16         ID      int
  17         matches int
  18         count  int
  19         winners mapset.Set[int]
  20         cards mapset.Set[int]
  21 }
  22
  23 func Part1(input string) int {
  24         games, err := parseGames(input)
  25         if err != nil {
  26                 fmt.Println("Error:", err)
  27                 return -1
  28         }
  29
  30         points := 0.0
  31         for _, game := range games {
  32                 matches := len(game.cards.Intersect(game.winners).ToSlice())
  33                 if matches > 0 {
  34                         points += math.Pow(2, float64(matches - 1))
  35                 }
  36         }
  37         return int(points)
  38 }
  39
  40 func Part2(input string) int {
  41         games, err := parseGames(input)
  42         if err != nil {
  43                 fmt.Println("Error:", err)
  44                 return -1
  45         }
  46
  47         for i, game := range games {
  48                 matches := game.cards.Intersect(game.winners).ToSlice()
  49                 games[i].matches = len(matches)
  50                 games[i].count = 1
  51         }
  52
  53         for i:=0;i<len(games);i++{
  54                 for j:=0;j<games[i].count;j++ {
  55                         for k:=1;k<=games[i].matches;k++ {
  56                                 games[i+k].count++
  57                         }
  58                 }
  59         }
  60
  61         cards := 0
  62         for i:=0;i<len(games);i++{
  63                 cards += games[i].count
  64         }
  65         return cards
  66 }
  67
  68 func parseGames(input string) ([]Game, error) {
  69
  70         var game Game
  71         var games []Game
  72
  73         lines := strings.Split(input, "\n")
  74         for _, line := range lines {
  75                 reID := regexp.MustCompile(`Card\s*(\d+):(.*) \| (.*)`)
  76                 match := reID.FindStringSubmatch(line)
  77                 if len(match) != 4 {
  78                         return games, fmt.Errorf("unable to extract game")
  79                 }
  80
  81                 game.ID = utils.MustAtoi(match[1])
  82                 game.winners = getNumbers(match[2])
  83                 game.cards = getNumbers(match[3])
  84
  85                 games = append(games, game)
  86         }
  87         return games, nil
  88 }
  89
  90 func getNumbers(input string) mapset.Set[int] {
  91         tokens := strings.Fields(input)
  92         var numbers []int
  93         for _, token := range tokens {
  94                 num := utils.MustAtoi(token)
  95                 numbers = append(numbers, num)
  96         }
  97         return mapset.NewSet[int](numbers...)
  98 }