day7, part2

day7/daySevel.go

@@ -0,0 +1,151 @@
+package day7
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"slices"
+	"strconv"
+	"strings"
+)
+
+func Run() int {
+	fmt.Print("hello day 7")
+	filename := "day7/input"
+	input := ReadFile(filename)
+	slices.SortFunc(input, CompareHands)
+	// log.Printf("read the input %+v\n", input)
+	for _, hand := range input {
+		// fmt.Printf("%+v\n", hand)
+		fmt.Printf("%+s\t\t%d\n", hand.Cards, hand.HandType)
+	}
+	slices.SortFunc([]int{}, func(a int, b int) int { return 0 })
+	result := 0
+	for i, hand := range input {
+		result += (i+1) * hand.Bid
+	}
+	return result
+}
+
+type HandType int
+
+const (
+	HighCard = iota
+	OnePair
+	TwoPair
+	ThreeKind
+	FullHouse
+	FourKind
+	FiveKind
+)
+
+type Hand struct {
+	Cards    string
+	Grouped  map[rune]int
+	HandType HandType
+	Bid      int
+}
+
+// cmp(a, b) should return a negative number when a < b, a positive number when
+// a > b and zero when a == b.
+const values string = "J23456789TQKA"
+
+func CompareHands(a Hand, b Hand) int {
+	if a.HandType != b.HandType {
+		return int(a.HandType) - int(b.HandType)
+	}
+	return compareString(a.Cards, b.Cards)
+}
+
+func compareString(a string, b string) int {
+	for i := 0; i < len(a); i++ {
+		if a[i] == b[i] {
+			continue
+		}
+		aVal := strings.IndexRune(values, rune(a[i]))
+		bVal := strings.IndexRune(values, rune(b[i]))
+		return aVal - bVal
+	}
+	return 0
+}
+
+func GetHandType(groupped map[rune]int) HandType {
+	var handType HandType
+	jokerSize, found := groupped['J']
+	if !found {
+		jokerSize = 0
+	}
+	sizes := make([]int, 0, len(groupped))
+	for card, size := range groupped {
+		if card != 'J' {
+			sizes = append(sizes, size)
+		}
+	}
+	slices.SortFunc(sizes, func (a, b int) int { return b - a })
+	var highest int
+	if len(sizes) == 0 {
+		highest = jokerSize
+	} else {
+		highest = sizes[0] + jokerSize
+	}
+	if highest == 5 {
+		return FiveKind
+	}
+	if highest == 4 {
+		return FourKind
+	}
+	other := sizes[1]
+	if highest == 3 {
+		if other == 2 {
+			return FullHouse
+		}
+		return ThreeKind
+	}
+	if highest == 2 {
+		if other == 2 {
+			return TwoPair
+		}
+		return OnePair
+	}
+
+	// log.Printf("calc type for %+v.\nsizes: %+v;\n %d", groupped, sizes, handType)
+	return handType
+}
+
+func ReadFile(filename string) []Hand {
+	bytes, err := os.ReadFile(filename)
+	if err != nil {
+		panic(fmt.Sprintln("error reading file : ", filename))
+	}
+	text := string(bytes)
+	lines := strings.Split(text, "\n")
+	linesLen := len(lines)
+	result := make([]Hand, 0, linesLen)
+
+	for _, line := range lines {
+		log.Println("reading in line : ", line)
+		if line == "" {
+			continue
+		}
+		firstSplit := strings.Fields(line)
+		cards := firstSplit[0]
+		bidStr := firstSplit[1]
+		bid, err := strconv.Atoi(bidStr)
+		if err != nil {
+			panic(fmt.Sprintln("error getting bid from : ", bidStr))
+		}
+		groupped := make(map[rune]int, 0)
+		for _, card := range cards {
+			groupped[card] += 1
+		}
+		hand := Hand{
+			Cards:   cards,
+			Grouped: groupped,
+			Bid:     bid,
+			HandType: GetHandType(groupped),
+		}
+		result = append(result, hand)
+	}
+
+	return result
+}

day7/example

@@ -0,0 +1,5 @@
+32T3K 765
+T55J5 684
+KK677 28
+KTJJT 220
+QQQJA 483

main.go

@@ -3,11 +3,11 @@ package main
 import (
 	"log"
 
-	"sunshine.industries/aoc2023/day6"
+	"sunshine.industries/aoc2023/day7"
 )
 
 func main() {
 	log.Print("> starting run:")
-	result := day6.Run()
-	log.Printf("day4 result: %d\n****\n", result)
+	result := day7.Run()
+	log.Printf("day7 result: %d\n****\n", result)
 }