refactor!: invert repo directory structure

now is language first

1 files changed, 273 insertions, 0 deletions

diff --git a/go/2023/internal/day_07/part_01/part_01.go b/go/2023/internal/day_07/part_01/part_01.go
new file mode 100644
index 0000000..a485dfd
--- /dev/null
+++ b/go/2023/internal/day_07/part_01/part_01.go
@@ -0,0 +1,273 @@
+package part_01
+
+import (
+	"os"
+	"strconv"
+	"strings"
+)
+
+const USE_SAMPLE = false
+
+type handType int
+
+const (
+	HIGH_CARD handType = iota
+	PAIR
+	TWO_PAIR
+	THREE_OF_A_KIND
+	FULL_HOUSE
+	FOUR_OF_A_KIND
+	FIVE_OF_A_KIND
+)
+
+func (h handType) String() string {
+	return [...]string{"HIGH_CARD", "PAIR", "TWO_PAIR", "THREE_OF_A_KIND", "FULL_HOUSE", "FOUR_OF_A_KIND", "FIVE_OF_A_KIND"}[h]
+}
+
+type cardType int
+
+const (
+	TWO cardType = iota
+	THREE
+	FOUR
+	FIVE
+	SIX
+	SEVEN
+	EIGHT
+	NINE
+	TEN
+	JACK
+	QUEEN
+	KING
+	ACE
+)
+
+func (c cardType) String() string {
+	return [...]string{"TWO", "THREE", "FOUR", "FIVE", "SIX", "SEVEN", "EIGHT", "NINE", "TEN", "JACK", "QUEEN", "KING", "ACE"}[c]
+}
+
+type hand struct {
+	strength handType
+	cards    []cardType
+	bet      int
+}
+
+/**
+ * Tried:
+ * - 252489894 (too high)
+ * - 229176554 (too low)
+ * - 200253108 (too low)
+ */
+func Solve() {
+	var filePath string
+	if USE_SAMPLE {
+		filePath = "../_input/day_07_part_01_sample.txt"
+	} else {
+		filePath = "../_input/day_07.txt"
+	}
+	contents, err := os.ReadFile(filePath)
+	if err != nil {
+		panic(err)
+	}
+
+	lines := strings.Split(string(contents), "\r\n")
+	var hands []hand
+	for _, line := range lines {
+		if line == "" {
+			continue
+		}
+
+		hands = append(hands, parseLine(line))
+	}
+
+	mappedByStrength := mapByStrength(hands)
+
+	sortedByHighest := make(map[handType][]hand)
+	for _, strength := range []handType{HIGH_CARD, PAIR, TWO_PAIR, THREE_OF_A_KIND, FULL_HOUSE, FOUR_OF_A_KIND, FIVE_OF_A_KIND} {
+		if _, ok := mappedByStrength[strength]; !ok {
+			continue
+		}
+
+		toBeSorted := mappedByStrength[strength]
+		sortedByHighest[strength] = sortByHighest(toBeSorted)
+	}
+
+	flattened := flatten(sortedByHighest)
+
+	answer := calculateWinnings(flattened)
+
+	println("Answer: ", answer)
+}
+
+func parseLine(line string) hand {
+	parts := strings.Split(line, " ")
+
+	unparsedCards := strings.Split(parts[0], "")
+	cards := parseCards(unparsedCards)
+	strength := calculateStrength(cards)
+
+	bet, err := strconv.Atoi(parts[1])
+	if err != nil {
+		panic(err)
+	}
+
+	return hand{
+		strength,
+		cards,
+		bet,
+	}
+}
+
+func parseCards(unparsedCards []string) []cardType {
+	var cards []cardType
+	for _, card := range unparsedCards {
+		switch card {
+		case "2":
+			cards = append(cards, TWO)
+		case "3":
+			cards = append(cards, THREE)
+		case "4":
+			cards = append(cards, FOUR)
+		case "5":
+			cards = append(cards, FIVE)
+		case "6":
+			cards = append(cards, SIX)
+		case "7":
+			cards = append(cards, SEVEN)
+		case "8":
+			cards = append(cards, EIGHT)
+		case "9":
+			cards = append(cards, NINE)
+		case "T":
+			cards = append(cards, TEN)
+		case "J":
+			cards = append(cards, JACK)
+		case "Q":
+			cards = append(cards, QUEEN)
+		case "K":
+			cards = append(cards, KING)
+		case "A":
+			cards = append(cards, ACE)
+		}
+	}
+	return cards
+}
+
+func calculateStrength(cards []cardType) handType {
+	strength := map[cardType]int{}
+	for _, card := range cards {
+		if _, ok := strength[card]; !ok {
+			strength[card] = 0
+		}
+		strength[card]++
+	}
+
+	var pairs int
+	var hasThreeOfAKind bool
+	for _, count := range strength {
+		if count == 5 {
+			return FIVE_OF_A_KIND
+		}
+
+		if count == 4 {
+			return FOUR_OF_A_KIND
+		}
+
+		if count == 3 {
+			hasThreeOfAKind = true
+		}
+
+		if count == 2 {
+			pairs++
+		}
+	}
+
+	if hasThreeOfAKind && pairs == 1 {
+		return FULL_HOUSE
+	}
+
+	if hasThreeOfAKind {
+		return THREE_OF_A_KIND
+	}
+
+	if pairs == 2 {
+		return TWO_PAIR
+	}
+
+	if pairs == 1 {
+		return PAIR
+	}
+
+	return HIGH_CARD
+}
+
+func mapByStrength(hands []hand) map[handType][]hand {
+
+	handsByStrength := make(map[handType][]hand)
+	for _, hand := range hands {
+		handsByStrength[hand.strength] = append(handsByStrength[hand.strength], hand)
+	}
+
+	return handsByStrength
+}
+
+// low to high
+func sortByHighest(hands []hand) []hand {
+	var partition = func(arr []hand, low, high int) ([]hand, int) {
+		pivot := arr[high]
+		index := low
+
+		for i := low; i < high; i++ {
+			// Always 5 cards
+			for j := 0; j < 5; j++ {
+				if arr[i].cards[j] < pivot.cards[j] {
+					arr[i], arr[index] = arr[index], arr[i]
+					index++
+					break
+				}
+
+				if arr[i].cards[j] != pivot.cards[j] {
+					break
+				}
+			}
+		}
+
+		arr[high], arr[index] = arr[index], arr[high]
+
+		return arr, index
+	}
+
+	var quickSort func(arr []hand, low, high int) []hand
+	quickSort = func(arr []hand, low, high int) []hand {
+		if low < high {
+			arr, pivot := partition(arr, low, high)
+
+			quickSort(arr, low, pivot-1)
+			quickSort(arr, pivot+1, high)
+		}
+
+		return arr
+	}
+
+	hands = quickSort(hands, 0, len(hands)-1)
+
+	return hands
+}
+
+func flatten(hands map[handType][]hand) []hand {
+	var flat []hand
+	for _, handType := range []handType{HIGH_CARD, PAIR, TWO_PAIR, THREE_OF_A_KIND, FULL_HOUSE, FOUR_OF_A_KIND, FIVE_OF_A_KIND} {
+		flat = append(flat, hands[handType]...)
+	}
+	return flat
+}
+
+func calculateWinnings(hands []hand) int {
+	var winnings int
+	for i, hand := range hands {
+		earned := hand.bet * (i + 1)
+		winnings += earned
+		println("hand ", i, ": { strength: ", hand.strength.String(), ", cards: [", hand.cards[0], hand.cards[1], hand.cards[2], hand.cards[3], hand.cards[4], "], earned: ", earned, " }")
+	}
+	return winnings
+}