From 8ef70e1659f401aad4877352df3b3c46d53b97e8 Mon Sep 17 00:00:00 2001
From: Alice <alicesunhi@gmail.com>
Date: Wed, 26 Feb 2020 19:05:21 -0800
Subject: [PATCH 1/2] tree

---
 lib/tree.rb | 105 +++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 88 insertions(+), 17 deletions(-)

diff --git a/lib/tree.rb b/lib/tree.rb
index c0d4b51..fc97dd8 100644
--- a/lib/tree.rb
+++ b/lib/tree.rb
@@ -1,13 +1,13 @@
 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
@@ -15,50 +15,121 @@ class Tree
   def initialize
     @root = nil
   end
-
+  
   # Time Complexity: 
   # Space Complexity: 
   def add(key, value)
-    raise NotImplementedError
+    if @root.nil?
+      @root = TreeNode.new(key, value)
+    else
+      add_helper(@root, key, value)
+    end
   end
-
+  
+  def add_helper(current, key, value)
+    if current.nil?
+      return TreeNode.new(key, value)
+    else
+      if key < current.key
+        current.left = add_helper(current.left, key, value)
+      else
+        current.right = add_helper(current.right, key, value)
+      end
+    end
+    return current
+  end
+  
   # Time Complexity: 
   # Space Complexity: 
   def find(key)
-    raise NotImplementedError
+    return nil if @root.nil?
+    
+    find_helper(@root, key)
   end
-
+  
+  def find_helper(current, key)
+    return nil if current.nil?
+    
+    if key == current.key
+      return current.value
+    elsif key < current.key
+      find_helper(current.left, key)
+    else
+      find_helper(current.right, key)
+    end
+    
+  end
+  
   # Time Complexity: 
   # Space Complexity: 
   def inorder
-    raise NotImplementedError
+    inorder_helper(@root, [])
   end
-
+  
+  def inorder_helper(current, list)
+    return list if current.nil?
+    
+    inorder_helper(current.left, list)
+    list << {key: current.key, value: current.value}
+    inorder_helper(current.right, list)
+  end
+  
   # Time Complexity: 
   # Space Complexity: 
   def preorder
-    raise NotImplementedError
+    preorder_helper(@root, [])
   end
-
+  
+  def preorder_helper(current, list)
+    return list if current.nil?
+    
+    list << {key: current.key, value: current.value}
+    preorder_helper(current.left, list)
+    preorder_helper(current.right, list)
+  end
+  
   # Time Complexity: 
   # Space Complexity: 
   def postorder
-    raise NotImplementedError
+    postorder_helper(@root, [])
   end
-
+  
+  def postorder_helper(current, list)
+    return list if current.nil?
+    
+    postorder_helper(current.left, list)
+    postorder_helper(current.right, list)
+    list << {key: current.key, value: current.value}
+  end
+  
   # Time Complexity: 
   # Space Complexity: 
   def height
-    raise NotImplementedError
+    return 0 if @root.nil?
+    
+    height_helper(@root, 0)
+  end
+  
+  def height_helper(current, height)
+    return height if current.nil?
+    
+    height +=1
+    left = height_helper(current.left, height)
+    right = height_helper(current.right, height)
+    
+    if left > right
+      return left
+    else
+      return right
+    end
   end
-
   # Optional Method
   # Time Complexity: 
   # Space Complexity: 
   def bfs
     raise NotImplementedError
   end
-
+  
   # Useful for printing
   def to_s
     return "#{self.inorder}"

From 35b5b4434c9252933df0d9ffafd9ea6778d2922c Mon Sep 17 00:00:00 2001
From: Alice <alicesunhi@gmail.com>
Date: Thu, 27 Feb 2020 12:42:04 -0800
Subject: [PATCH 2/2]  i forgot to save

---
 lib/tree.rb | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/lib/tree.rb b/lib/tree.rb
index fc97dd8..ec3c845 100644
--- a/lib/tree.rb
+++ b/lib/tree.rb
@@ -16,8 +16,8 @@ def initialize
     @root = nil
   end
   
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(log n) for a balanced tree, O(n) for unbalanced
+  # Space Complexity: O(log n) for a balanced tree, O(n) for unbalanced
   def add(key, value)
     if @root.nil?
       @root = TreeNode.new(key, value)
@@ -39,8 +39,8 @@ def add_helper(current, key, value)
     return current
   end
   
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(log n) for a balanced tree, O(n) for unbalanced
+  # Space Complexity: O(log n) for a balanced tree, O(n) for unbalanced
   def find(key)
     return nil if @root.nil?
     
@@ -60,8 +60,8 @@ def find_helper(current, key)
     
   end
   
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def inorder
     inorder_helper(@root, [])
   end
@@ -74,8 +74,8 @@ def inorder_helper(current, list)
     inorder_helper(current.right, list)
   end
   
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def preorder
     preorder_helper(@root, [])
   end
@@ -88,8 +88,8 @@ def preorder_helper(current, list)
     preorder_helper(current.right, list)
   end
   
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def postorder
     postorder_helper(@root, [])
   end
@@ -102,8 +102,8 @@ def postorder_helper(current, list)
     list << {key: current.key, value: current.value}
   end
   
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def height
     return 0 if @root.nil?