diff --git a/lib/tree.rb b/lib/tree.rb
index c0d4b51..d89068e 100644
--- a/lib/tree.rb
+++ b/lib/tree.rb
@@ -1,62 +1,243 @@
+QUEUE_SIZE = 20
+
+class Queue
+  def initialize
+    @store = Array.new(QUEUE_SIZE)
+    @front = @rear = -1
+  end
+
+  def enqueue(element)
+    if @front == -1 # Q is empty
+      @rear = 1
+      @front = 0
+      @store[@front] = element
+    elsif @front == @rear && !self.empty?
+      raise Error, "Q IS FULL"
+    else #not empty
+      new_rear = (@rear + 1) % QUEUE_SIZE
+      @store[@rear] = element
+      @rear = new_rear
+    end
+  end
+
+  def dequeue
+    if @front == -1
+      return nil
+    end
+    index_to_remove = @front
+    value_to_remove = @store[index_to_remove]
+    @store[index_to_remove] = nil
+    @front += 1
+    return value_to_remove
+  end
+
+  def front
+    return @store[@front]
+  end
+
+  def size
+    size = 0
+    return 0 if self.empty?
+
+    @store.each do |i|
+      if i != nil
+        size += 1
+      end
+    end
+
+    return size
+  end
+
+  def empty?
+    return true if self.to_s == "[]"
+    return false
+  end
+
+  def to_s
+    values = []
+    @store.each do |i|
+      if i != nil
+        values << i
+      end
+    end
+
+    return values.to_s
+  end
+end
+
 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
+
+  def add(key, value)
+    new_node = TreeNode.new(key, value)
+    if new_node.key <= @key
+      if @left == nil
+        @left = new_node
+      else
+        @left.add(key, value)
+      end
+    else
+      if @right == nil
+        @right = new_node
+      else
+        @right.add(key, value)
+      end
+    end
+  end
+
+  def inorder(array)
+    if @left != nil
+      @left.inorder(array)
+    end
+
+    array << {key: @key, value: @value}
+
+    if @right != nil
+      @right.inorder(array)
+    end
+  end
+
+  def preorder(array)
+    array << {key: @key, value: @value}
+
+    if @left != nil
+      @left.preorder(array)
+    end
+
+    if @right != nil
+      @right.preorder(array)
+    end
+  end
+
+  def postorder(array)
+    if @left != nil
+      @left.postorder(array)
+    end
+
+    if @right != nil
+      @right.postorder(array)
+    end
+
+    array << {key: @key, value: @value}
+  end
 end
 
 class Tree
   attr_reader :root
+
   def initialize
     @root = nil
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(log n) if the tree is balanced, where n is the number of nodes in the tree.
+  # Space Complexity: O(1)
   def add(key, value)
-    raise NotImplementedError
+    if @root == nil
+      @root = TreeNode.new(key, value)
+    else
+      @root.add(key, value)
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(log n) if the tree is balanced, where n is the number of nodes in the tree.
+  # Space Complexity: O(1)
   def find(key)
-    raise NotImplementedError
+    current = @root
+
+    if current == nil
+      return nil
+    end
+
+    while current != nil
+      if key == current.key
+        return current.value
+      elsif key <= current.key
+        current = current.left
+      else
+        current = current.right
+      end
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n) where n is the number of nodes in the tree
+  # Space Complexity: O(n) where n is the number of nodes in the tree
+  # left root right
   def inorder
-    raise NotImplementedError
+    current = @root
+    values = []
+    if current != nil
+      current.inorder(values)
+    end
+    return values
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n) where n is the number of nodes in the tree
+  # Space Complexity: O(n) where n is the number of nodes in the tree
   def preorder
-    raise NotImplementedError
+    current = @root
+    values = []
+    if current != nil
+      current.preorder(values)
+    end
+    return values
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n) where n is the number of nodes in the tree
+  # Space Complexity: O(n) where n is the number of nodes in the tree
   def postorder
-    raise NotImplementedError
+    current = @root
+    values = []
+    if current != nil
+      current.postorder(values)
+    end
+    return values
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
-  def height
-    raise NotImplementedError
+  # Time Complexity: O(n) where n is the number of nodes in the tree
+  # Space Complexity: O(1)
+  def height(node)
+    if node == nil
+      return 0
+    else
+      left_height = height(node.left)
+      right_height = height(node.right)
+      if left_height >= right_height
+        return 1 + left_height
+      else
+        return 1 + right_height
+      end
+    end
   end
 
   # Optional Method
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n) where n is the number of nodes in the tree
+  # Space Complexity: O(n) where n is the number of nodes in the tree
   def bfs
-    raise NotImplementedError
+    if @root == nil
+      return []
+    end
+
+    queue = Queue.new
+    queue.enqueue(@root)
+    bfs_values = []
+
+    while queue.size > 0
+      node = queue.front
+      bfs_values << {key: node.key, value: node.value}
+      queue.enqueue(node.left) unless node.left == nil
+      queue.enqueue(node.right) unless node.right == nil
+      queue.dequeue
+    end
+
+    return bfs_values
   end
 
   # Useful for printing
diff --git a/test/tree_test.rb b/test/tree_test.rb
index 222b693..a491220 100644
--- a/test/tree_test.rb
+++ b/test/tree_test.rb
@@ -1,10 +1,9 @@
-require_relative 'test_helper'
-
+require_relative "test_helper"
 
 Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
 
 describe Tree do
-  let (:tree) {Tree.new}
+  let (:tree) { Tree.new }
 
   let (:tree_with_nodes) {
     tree.add(5, "Peter")
@@ -37,23 +36,21 @@
     end
 
     it "will return the tree in order" do
-
-      expect(tree_with_nodes.inorder).must_equal [{:key=>1, :value=>"Mary"}, {:key=>3, :value=>"Paul"}, 
-                                       {:key=>5, :value=>"Peter"}, {:key=>10, :value=>"Karla"}, 
-                                       {:key=>15, :value=>"Ada"}, {:key=>25, :value=>"Kari"}]
+      expect(tree_with_nodes.inorder).must_equal [{:key => 1, :value => "Mary"}, {:key => 3, :value => "Paul"},
+                                                  {:key => 5, :value => "Peter"}, {:key => 10, :value => "Karla"},
+                                                  {:key => 15, :value => "Ada"}, {:key => 25, :value => "Kari"}]
     end
   end
 
-
   describe "preorder" do
     it "will give an empty array for an empty tree" do
       expect(tree.preorder).must_equal []
     end
 
     it "will return the tree in preorder" do
-      expect(tree_with_nodes.preorder).must_equal [{:key=>5, :value=>"Peter"}, {:key=>3, :value=>"Paul"}, 
-                                        {:key=>1, :value=>"Mary"}, {:key=>10, :value=>"Karla"}, 
-                                        {:key=>15, :value=>"Ada"}, {:key=>25, :value=>"Kari"}]
+      expect(tree_with_nodes.preorder).must_equal [{:key => 5, :value => "Peter"}, {:key => 3, :value => "Paul"},
+                                                   {:key => 1, :value => "Mary"}, {:key => 10, :value => "Karla"},
+                                                   {:key => 15, :value => "Ada"}, {:key => 25, :value => "Kari"}]
     end
   end
 
@@ -63,19 +60,19 @@
     end
 
     it "will return the tree in postorder" do
-      expect(tree_with_nodes.postorder).must_equal [{:key=>1, :value=>"Mary"}, {:key=>3, :value=>"Paul"}, 
-                                         {:key=>25, :value=>"Kari"}, {:key=>15, :value=>"Ada"}, 
-                                         {:key=>10, :value=>"Karla"}, {:key=>5, :value=>"Peter"}]
+      expect(tree_with_nodes.postorder).must_equal [{:key => 1, :value => "Mary"}, {:key => 3, :value => "Paul"},
+                                                    {:key => 25, :value => "Kari"}, {:key => 15, :value => "Ada"},
+                                                    {:key => 10, :value => "Karla"}, {:key => 5, :value => "Peter"}]
     end
   end
-  
+
   describe "height" do
     it "returns 0 for an empty tree" do
-      expect(tree.height).must_equal 0
+      expect(tree.height(tree.root)).must_equal 0
     end
 
     it "returns correct height of tree" do
-      expect(tree_with_nodes.height).must_equal 4
+      expect(tree_with_nodes.height(tree.root)).must_equal 4
     end
   end
 
@@ -85,8 +82,8 @@
     end
 
     it "will return an array of a level-by-level output of the tree" do
-      expect(tree_with_nodes.bfs).must_equal [{:key=>5, :value=>"Peter"}, {:key=>3, :value=>"Paul"}, 
-                                   {:key=>10, :value=>"Karla"}, {:key=>1, :value=>"Mary"}, 
+      expect(tree_with_nodes.bfs).must_equal [{:key=>5, :value=>"Peter"}, {:key=>3, :value=>"Paul"},
+                                   {:key=>10, :value=>"Karla"}, {:key=>1, :value=>"Mary"},
                                    {:key=>15, :value=>"Ada"}, {:key=>25, :value=>"Kari"}]
     end
   end