Leaves - Georgina

lib/tree.rb

@@ -2,12 +2,12 @@ class TreeNode
   attr_reader :key, :value
   attr_accessor :left, :right
 
-   def initialize(key, val)
+  def initialize(key, val)
     @key = key
     @value = val
     @left = nil
     @right = nil
-   end
+  end
 end
 
 class Tree
@@ -16,40 +16,133 @@ def initialize
     @root = nil
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def add_while_loop(key, value)
+    if @root.nil?
+      @root = TreeNode.new(key, value)
+    else
+      current = @root
+      while true
+        if key < current.key
+          if !current.left.nil?
+            current = current.left
+          else
+            current.left = TreeNode.new(key, value)
+            return
+          end
+        else
+          if !current.right.nil?
+            current = current.right
+          else
+            current.right = TreeNode.new(key, value)
+            return
+          end
+        end
+      end
+    end
+  end
+
+  # Time Complexity: O(logn) 
+  # Space Complexity: O(logn) 
   def add(key, value)
-    raise NotImplementedError
+    @root = add_helper(@root, key, value)
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def add_helper(current_node, key, value)
+    return TreeNode.new(key, value) if current_node.nil?
+
+    if key < current_node.key
+      current_node.left = add_helper(current_node.left, key, value)
+    else
+      current_node.right = add_helper(current_node.right, key, value)
+    end
+
+    return current_node
+  end
+
+    # Time Complexity: O(logn) 
+  # Space Complexity: O(logn) 
   def find(key)
-    raise NotImplementedError
+    return nil if @root.nil?
+    return find_helper(@root, key).value
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def find_helper(current_node, key)
+    return current_node if current_node.key == key
+
+    if key < current_node.key
+      return find_helper(current_node.left, key)
+    else
+      return find_helper(current_node.right, key)
+    end
+  end
+
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def inorder
-    raise NotImplementedError
+    inorder_helper(@root, [])
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def inorder_helper(current_node, list)
+    return list if current_node.nil?
+
+    inorder_helper(current_node.left, list)
+    list << { key: current_node.key, value: current_node.value}
+
+    inorder_helper(current_node.right, list)
+
+    return list
+  end
+
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def preorder
-    raise NotImplementedError
+    preorder_helper(@root, [])
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def preorder_helper(current_node, list)
+    return list if current_node.nil?
+
+    list << { key: current_node.key, value: current_node.value}
+
+    preorder_helper(current_node.left, list)
+
+    preorder_helper(current_node.right, list)
+
+    return list
+  end
+
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def postorder
-    raise NotImplementedError
+    postorder_helper(@root, [])
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def postorder_helper(current_node, list)
+    return list if current_node.nil?
+
+    postorder_helper(current_node.left, list)
+
+    postorder_helper(current_node.right, list)
+
+    list << { key: current_node.key, value: current_node.value}
+
+    return list
+  end
+
+  # Time Complexity: O(n)
+  # Space Complexity: O(logn)
   def height
-    raise NotImplementedError
+    return height_helper(@root, i = 0)
+  end
+
+  def height_helper(current_node, i = 0)
+    return i if current_node.nil?
+
+    left = height_helper(current_node.left, i + 1)
+
+    right = height_helper(current_node.right, i + 1)
+
+    return [left, right].max
   end
 
   # Optional Method