Submission #611609

---

Source Code Expand

class Apex
  attr_reader :sides, :num, :h
  def initialize(num, h)
    @sides = []
    @h = h
    @num = num
  end
  def remove
    return false if h == 1 || @sides.size != 1
    sides.first.remove
    true
  end
end
class Side
  attr_reader :num
  def initialize(num, a, b)
    @num = num
    @apex0 = a
    @apex1 = b
    a.sides << self
    b.sides << self
  end
  def remove
    @apex0.sides.delete(self)
    @apex1.sides.delete(self)
  end
end

n, x = gets.split.map(&:to_i)
hs = gets.split.map(&:to_i)
hs[x - 1] = 1
n.times do |i|
  hs[i] = Apex.new(i, hs[i])
end
(n - 1).times do |i|
  a, b = gets.split.map{|s| s.to_i - 1}
  s = Side.new(i, hs[a], hs[b])
end
ans = (n - 1) * 2
loop do
  found = false
  hs.each do |h|
    if h.remove
      ans -= 2
      found = true
    end
  end
  break unless found
end

puts ans

Submission Info

Judge Result