67 lines
1.3 KiB
Crystal
67 lines
1.3 KiB
Crystal
|
require "advent"
|
||
|
|
first, second = input(2020, 22).split("\n\n")
|
||
|
|
first = first.lines[1..].map &.to_i32
|
||
|
|
second = second.lines[1..].map &.to_i32
|
||
|
|
|
||
|
|
class Array(T)
|
||
|
|
def pop_left
|
||
|
|
delete_at(0)
|
||
|
|
end
|
||
|
|
|
||
|
|
def score
|
||
|
|
total = 0
|
||
|
|
s = size
|
||
|
|
each_with_index do |n, i|
|
||
|
|
total += n * (s - i)
|
||
|
|
end
|
||
|
|
total
|
||
|
|
end
|
||
|
|
end
|
||
|
|
|
||
|
|
def no_rec(deck1, deck2)
|
||
|
|
while !deck1.empty? && !deck2.empty?
|
||
|
|
f, s = deck1.delete_at(0), deck2.delete_at(0)
|
||
|
|
if f > s
|
||
|
|
deck1 << f << s
|
||
|
|
else
|
||
|
|
deck2 << s << f
|
||
|
|
end
|
||
|
|
end
|
||
|
|
return !deck1.empty?
|
||
|
|
end
|
||
|
|
|
||
|
|
def rec(deck1, deck2)
|
||
|
|
seen = Set({Int32, Int32}).new
|
||
|
|
while !deck1.empty? && !deck2.empty?
|
||
|
|
key = {deck1.score, deck2.score}
|
||
|
|
return true if seen.includes?(key)
|
||
|
|
seen << key
|
||
|
|
|
||
|
|
f = deck1.delete_at(0)
|
||
|
|
s = deck2.delete_at(0)
|
||
|
|
|
||
|
|
p1wins = (f <= deck1.size) && (s <= deck2.size) ? rec(deck1[0..f-1], deck2[0..s-1]) : f > s
|
||
|
|
if p1wins
|
||
|
|
deck1 << f << s
|
||
|
|
else
|
||
|
|
deck2 << s << f
|
||
|
|
end
|
||
|
|
end
|
||
|
|
return !deck1.empty?
|
||
|
|
end
|
||
|
|
|
||
|
|
def run(first, second, proc)
|
||
|
|
((proc.call(first, second)) ? first : second).score
|
||
|
|
end
|
||
|
|
|
||
|
|
def part1(input)
|
||
|
|
run(input[0], input[1], ->no_rec(Array(Int32), Array(Int32)))
|
||
|
|
end
|
||
|
|
|
||
|
|
def part2(input)
|
||
|
|
run(input[0], input[1], ->rec(Array(Int32), Array(Int32)))
|
||
|
|
end
|
||
|
|
|
||
|
|
puts part1({first, second}.clone)
|
||
|
|
puts part2({first, second}.clone)
|