tries_contacts.rb

class Node
  attr_accessor :children, :size

  def initialize
    @children = {}
    @size = 0
  end

  def find_count(word, index)
    return @size if index == word.length
    child = get_node(word[index])
    if !child
      return 0
    end
    return child.find_count(word, index + 1)
  end

  def add(word)
    add_word(word, 0)
  end

  def add_word(word, index)
    @size += 1
    return if index == word.length
    current = word[index]
    charCode = get_char_index(current)
    child = get_node(current)
    if !child
      child = Node.new
      set_node(current, child)
    end
    child.add_word(word, index + 1)
  end

  private

  def get_char_index(character)
    character.bytes[0] - 97
  end

  def get_node(character)
    @children[get_char_index(character)]
  end

  def set_node(character, node)
    @children[get_char_index(character)] = node
  end

end

n = gets.strip.to_i
node = Node.new
for a0 in (0..n-1)
    op,contact = gets.strip.split(' ')
    if op == 'add'
      node.add(contact)
    else
      puts node.find_count(contact, 0)
    end
end