AtCoder AGC #002 [Ruby]

agc002-a.rb

a, b = gets.chomp.split(" ").map(&:to_i)
if a > 0 then
  puts "Positive"
elsif a < 0 && b >= 0 then
  puts "Zero"
elsif (b - a + 1).even? then
  puts "Positive"
else
  puts "Negative"
end

agc002-b.rb

n, m = gets.chomp.split(" ").map(&:to_i)
box = Struct.new("Box", :red, :n)
boxes = Array.new(n+1){box.new(false, 1)}
boxes[1][:red] = true
m.times do
  x, y = gets.chomp.split(" ").map(&:to_i)
  if boxes[x][:red] then
    boxes[y][:red] = true
  end
  boxes[x][:n] = boxes[x][:n] - 1
  if boxes[x][:n] == 0 then
    boxes[x][:red] = false
  end
  boxes[y][:n] = boxes[y][:n] + 1  
end
res = 0
boxes.each do |bx|
  res += 1 if bx[:red] && (bx[:n] != 0)
end
puts res