You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
|
|
|
require "set"
|
|
|
|
|
|
|
|
motions = ARGF.read.scan(/([RLUD])\s+(\d+)/).map { [_1, _2.to_i] }
|
|
|
|
|
|
|
|
class Snake
|
|
|
|
def initialize
|
|
|
|
@knots = Array.new(10) { [0, 0] }
|
|
|
|
end
|
|
|
|
|
|
|
|
def tail = @knots.last
|
|
|
|
|
|
|
|
def move!(dir)
|
|
|
|
delta = case dir
|
|
|
|
when ?L then [ 0, -1]
|
|
|
|
when ?U then [ 1, 0]
|
|
|
|
when ?R then [ 0, 1]
|
|
|
|
when ?D then [-1, 0]
|
|
|
|
else fail dir.inspect
|
|
|
|
end
|
|
|
|
@knots[0] = @knots[0].zip(delta).map { _1 + _2 }
|
|
|
|
|
|
|
|
(0...@knots.size-1).each do |i|
|
|
|
|
head = @knots[i]
|
|
|
|
tail = @knots[i+1]
|
|
|
|
|
|
|
|
delta = head.zip(tail).map { _1 - _2 }
|
|
|
|
if delta.any? { _1.abs > 1 }
|
|
|
|
@knots[i+1] = tail.zip(delta.map { _1.clamp(-1, 1) }).map { _1 + _2 }
|
|
|
|
end
|
|
|
|
end
|
|
|
|
end
|
|
|
|
end
|
|
|
|
|
|
|
|
snake = Snake.new
|
|
|
|
seen = Set.new
|
|
|
|
|
|
|
|
motions.each do |dir, distance|
|
|
|
|
distance.times do
|
|
|
|
snake.move!(dir)
|
|
|
|
seen << snake.tail
|
|
|
|
end
|
|
|
|
end
|
|
|
|
|
|
|
|
p seen.size
|