Key to CSE341 Section #9 Problems

1. One possible solution appears below:
        class Point
          def initialize (x = 0, y = 0)
            @x = x
            @y = y
          end
        
          attr_reader :x, :y
          attr_writer :x, :y
        
          def to_s
            "(#{@x}, #{@y})"
          end
        end

2. One possible solution appears below:
        class Tree
          def initialize()
            @overallRoot = nil
          end
        
          def insert(v)
            @overallRoot = insert_helper(v, @overallRoot)
          end
        
          def print()
            print_helper(@overallRoot)
          end
        
          private # beginning of private definitions
        
          class Node
            def initialize(data = nil, left = nil, right = nil)
              @data = data
              @left = left
              @right = right
            end
        
            attr_reader :data, :left, :right
            attr_writer :data, :left, :right
          end
        
          def insert_helper(v, root)
            if root == nil
              root = Node.new(v)
            elsif v < root.data then
              root.left = insert_helper(v, root.left)
            else
              root.right = insert_helper(v, root.right)
            end
            return root
          end
        
          def print_helper(root)
            if root != nil then
              print_helper root.left
              puts root.data
              print_helper root.right
            end
          end
        end

3. One possible solution appears below:
        t = Tree.new
        10.times do
          n = rand(100)
	  print "inserting ", n, "\n"
          t.insert n
        end
	t.print

   An alternative way to print would be:
       puts "inserting " + n.to_s

4. The Ruby interpreter will tell us the answers if we type in:
        3.8.class
	3.8.class.class
	3.8.class.class.methods
	3.8.class.superclass