dfs.rb

# In the above example it will check to see if the payload is 11 in the following order: 2, 7, 6, 5 when 
# it gets to 5 and 5 has no children, it will return to the 6 and go to any children 6 has. 6 has a 
# remaining child, which is 11 so that node is checked and since that value is the correct value it 
# will be returned and searching will stop.

class Tree
    attr_accessor :payload, :children

    def initialize(payload, children)
        @payload = payload
        @children = children
    end

end


# The "Leafs" of a tree, elements that have no children
fifth_node    = Tree.new(5, [])
eleventh_node = Tree.new(11, [])
fourth_node   = Tree.new(4, [])


# The "Branches" of the tree
ninth_node = Tree.new(9, [fourth_node])
sixth_node = Tree.new(6, [fifth_node, eleventh_node])
seventh_node = Tree.new(7, [sixth_node])
fifth_node = Tree.new(5, [ninth_node])

# The "Trunk" of the tree
trunk = Tree.new(2, [seventh_node, fifth_node])


def depth_first_search(value,node)
  @current_node = node
  if @current_node.payload == value
    puts "Destination Node #{@current_node.payload}"
    return @current_node
  else
    puts "Go to next Node #{@current_node.payload}"
    if @current_node.children != nil
        @current_node.children.each do |x|  
          depth_first_search(value, x)
        end
    end
  end
end

depth_first_search(11, trunk)