aoc2023/day-7/hands.go

package main

var hands = []*hand{}

type hand struct {
	cards    string
	bid      int
	matches  map[rune]int
	numPairs int
	_kind    int
}

func newHand(cards string, bid int) *hand {
	h := &hand{cards: cards, bid: bid}
	setKind(h)
	return h
}

func (h *hand) kind() int {
	return h._kind
}

func (h *hand) getMatches() map[rune]int {
	if h.matches == nil {
		h.matches = matches(h.cards)
	}
	return h.matches
}

func setKind(h *hand) {
	if isFiveOfAKind(h) {
		h._kind = fiveofakind
	} else if isHighCard(h) {
		h._kind = highcard
	} else if isFourOfAKind(h) {
		h._kind = fourofakind
	} else if isFullHouse(h) {
		h._kind = fullhouse
	} else if isThreeOfAKind(h) {
		h._kind = threeofakind
	} else if isTwoPair(h) {
		h._kind = twopair
	} else if isOnePair(h) {
		h._kind = onepair
	}
}

func isFiveOfAKind(h *hand) bool {
	return len(h.getMatches()) == 1
}

func isHighCard(h *hand) bool {
	return len(h.getMatches()) == 5
}

func isFourOfAKind(h *hand) bool {
	if len(h.getMatches()) == 2 {
		for _, c := range h.matches {
			if c == 4 {
				return true
			}
		}
		return false
	}
	return false
}

func isFullHouse(h *hand) bool {
	if len(h.getMatches()) == 2 {
		return !isFourOfAKind(h)
	}
	return false
}

func isThreeOfAKind(h *hand) bool {
	if len(h.getMatches()) == 3 {
		for _, c := range h.matches {
			if c == 3 {
				return true
			}
		}
		return false
	}
	return false
}

func getNumPairs(h *hand) int {
	if h.numPairs == 0 {
		allowed := []int{1, 2}
		for _, n := range h.getMatches() {
			if !contains(allowed, n) {
				return -1 // there may be a pair but its a fullhouse
			}
			if n == 2 {
				h.numPairs++
			}
		}
	}
	return h.numPairs
}

func isTwoPair(h *hand) bool {
	return getNumPairs(h) == 2
}

func isOnePair(h *hand) bool {
	return !isTwoPair(h) && h.numPairs == 1
}