postfixhints.rb

class TreeNode
  attr_accessor :val, :left, :right
  def initialize(v)
    @val = v
  end

  def leaf?
    # A node is a leaf if it has no children.
  end
end
def numeric?(str)
  true if Float(str) rescue false
end

def parse_postfix_expression(exp)
  # Split our arithmetic expression at the whitespaces.
  # Since we are parsing postfix, the root node will always be the last token.
end

def get_next_node(tokens)
  # The next token will be the root of the tree we are building.

  # If we are a number node, we are a leaf, so skip this.

  # The second token will be the beginning of the right subtree.

  # After the left subtree will come the left subtree.
  
end

data = File.read("data").split("\n").map {|l| parse_postfix_expression(l)}