@input = File.read("5.input").split("\n")

def stacks()
  return @input.filter {|line| line.include?("[")}.map{|line| line.chars.each_slice(4).to_a.map{|block| block[1]}}.transpose.map{|stack| stack.filter{|box| box != " "}.reverse}
end

@instrs = @input.filter{|line| line.include?("move")}.map{|line| line.split(/[a-z ]+/)}

def part1()
  stacks = stacks()

  @instrs.each do |inst|
    (_, cnt, from, to) = inst.map{|i| i.to_i}

    (1..cnt).each do |_|
      box = stacks[from - 1].pop()
      stacks[to - 1].append(box)
    end
  end

  puts stacks.map{|s| s[-1]}.join()
end

def part2()
  stacks = stacks()

  @instrs.each do |inst|
    (_, cnt, from, to) = inst.map{|i| i.to_i}

    boxes = stacks[from - 1].pop(cnt)
    stacks[to - 1] = stacks[to - 1].concat(boxes)
  end

  puts stacks.map{|s| s[-1]}.join()
end

part1()
part2()