Space - Faezeh

lib/tree.rb

@@ -16,40 +16,181 @@ def initialize
     @root = nil
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(Log n)
+  # Space Complexity: O(1)
   def add(key, value)
-    raise NotImplementedError
+    # raise NotImplementedError
+    new_node = TreeNode.new(key, value)
+
+    if @root.nil?
+      @root = new_node
+    else
+      add_helper(@root, new_node)
+    end
+
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def add_helper(current, new_node)
+    return new_node if current.nil?
+
+    if new_node.key <= current.key
+      current.left = add_helper(current.left, new_node)
+    else
+      current.right = add_helper(current.right, new_node)
+    end
+
+    current
+  end
+
+  # Time Complexity: O(log n)
+  # Space Complexity: O(1)
   def find(key)
-    raise NotImplementedError
+    # raise NotImplementedError
+    current = @root
+    return nil if current.nil?
+
+    if current.key == key
+      return current.value
+    else
+      find_helper(current, key)
+    end
+
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def find_helper(current, key)
+    return current.value if key == current.key
+
+    if key <= current.key
+      find_helper(current.left, key)
+    else
+      find_helper(current.right, key)
+    end
+  end
+
+  # Me, Yieni and Haben got together to do the traverse methods.
+  # We found this link but worked on it for a few hours to understand
+  # http://rubyalgorithms.com/binary_search_tree.html
+  # whet &block and yield are doing before using them
+
+  # Time Complexity: O(Log n)
+  # Space Complexity: O(n)
   def inorder
-    raise NotImplementedError
+    # raise NotImplementedError
+    root = @root
+    traverse_array = []
+    return traverse_array if root.nil?
+
+    inorder_helper(root) do |node|
+      traverse_array << { key: node.key, value: node.value }
+    end
+
+    traverse_array
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # any method in ruby can take a block
+  # &block is usuful for sending in the block when we want to pass it on
+  # but with yield alone we did not need to pass in the &block into the main
+  # inorder_helper method
+  # if we want to use block.call(node) we need to pass in &block in the main
+  # helper method
+
+  # yield returns the variable - the information back up :)
+
+  def inorder_helper(node, &block)
+    return if node.nil?
+
+    inorder_helper(node.left, &block)
+    yield node
+    inorder_helper(node.right, &block)
+  end
+
+  # Haben's refactor
+  # def inorder_recursion(current, traverse_array)
+  #   return if current.nil?
+  #   inorder_recursion(current.left, traverse_array) # process left side
+  #   traverse_array << { key: current.key, value: current.value }
+  #   inorder_recursion(current.right, traverse_array) # process right side
+  # end
+  # def inorder
+  #   traverse_array = []
+  #   inorder_recursion(@root, traverse_array)
+  #   traverse_array
+  # end
+
+  # Time Complexity: O(Log n)
+  # Space Complexity: O(n)
   def preorder
-    raise NotImplementedError
+    # raise NotImplementedError
+    root = @root
+    traverse_array = []
+    return traverse_array if root.nil?
+
+    preorder_helper(root) do |node|
+      traverse_array << { key: node.key, value: node.value }
+    end
+
+    traverse_array
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def preorder_helper(node, &block)
+    return if node.nil?
+
+    yield node
+    preorder_helper(node.left, &block)
+    preorder_helper(node.right, &block)
+  end
+
+  # Time Complexity: O(Log n)
+  # Space Complexity: O(n)
   def postorder
-    raise NotImplementedError
+    # raise NotImplementedError
+    root = @root
+    traverse_array = []
+    return traverse_array if root.nil?
+
+    postorder_helper(root) do |node|
+      traverse_array << { key: node.key, value: node.value }
+    end
+
+    traverse_array
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def postorder_helper(node, &block)
+    return if node.nil?
+
+    postorder_helper(node.left, &block)
+    postorder_helper(node.right, &block)
+    yield node
+  end
+
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def height
-    raise NotImplementedError
+    # raise NotImplementedError
+    node = @root
+    return 0 if node.nil?
+
+    count_right = 0
+    count_left = 0
+
+    count_left = height_helper(node, 'left', count_left)
+    count_right = height_helper(node, 'right', count_right)
+
+    if count_right > count_left
+      return count_right
+    else
+      return count_left
+    end
+  end
+
+  def height_helper(node, side, count)
+    return count if node.nil?
+    count += 1
+    if side == 'left'
+      height_helper(node.left, 'left', count)
+    else
+      height_helper(node.right, 'right', count)
+    end
   end
 
   # Optional Method
@@ -63,4 +204,5 @@ def bfs
   def to_s
     return "#{self.inorder}"
   end
+
 end

test/test_helper.rb

@@ -1,4 +1,4 @@
-
+   
 require "minitest"
 require "minitest/autorun"
 require "minitest/reporters"

test/tree_test.rb

@@ -120,8 +120,6 @@
 
       my_tree = Tree.new
 
-      my_tree = Tree.new
-
       my_tree.add(100, "Paula")
       my_tree.add(90, "Ann")
       my_tree.add(80, "Grace")