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advent-of-code/2023/ruby/day_07.rb

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1.3 KiB

HAND_STRENGTH = [
[5], # five of a kind
[1, 4], # four of a kind
[2, 3], # full house
[1, 1, 3], # three of a kind
[1, 2, 2], # two pair
[1, 1, 1, 2], # one pair
[1, 1, 1, 1, 1], # high card
].reverse.each.with_index.to_h { [_1, _2] }
class PartOne
CARD_RANK = ((?2..?9).to_a + %w[ T J Q K A ]).each.with_index.to_h
def strength(cards)
tally = cards.tally
strengths = [
self.hand_type(tally),
*cards.map { CARD_RANK.fetch(_1) },
]
strengths.map { (?a.ord + _1).chr }.join
end
def hand_type(tally)
HAND_STRENGTH.fetch(tally.values.sort)
end
end
class PartTwo < PartOne
CARD_RANK = ([?J] + (?2..?9).to_a + %w[ T Q K A ]).each.with_index.to_h
def hand_type(tally)
jokers = tally.delete(?J) || 0
counts = tally.values.sort
if counts.empty?
counts = [5]
else
counts[-1] += jokers
end
HAND_STRENGTH.fetch(counts)
end
end
hands = ARGF.read.scan(/(\w+)\s+(\d+)/).to_h { [_1.chars, _2.to_i ] }
part_one = PartOne.new
p hands
.sort_by {|(hand,_)| part_one.strength(hand) }
.map.with_index {|(_,bid),i| bid * (i+1) }
.sum
part_two = PartTwo.new
p hands
.sort_by {|(hand,_)| part_two.strength(hand) }
.map.with_index {|(_,bid),i| bid * (i+1) }
.sum