diff --git a/binary_search_tree/tree.py b/binary_search_tree/tree.py
index cdd5abc..b643692 100644
--- a/binary_search_tree/tree.py
+++ b/binary_search_tree/tree.py
@@ -14,36 +14,127 @@ class Tree:
     def __init__(self):
         self.root = None
 
-    # Time Complexity: 
-    # Space Complexity: 
+    # Time Complexity: O(log n)
+    # Space Complexity: O(n)
     def add(self, key, value = None):
-        pass
+        node = TreeNode(key, value)
+        if self.root is None:
+            self.root = node
+            return self
+        
+        current = self.root
+        while current:
+            if current.key > key:
+                # Go left
+                if current.left is None:
+                    current.left = node
+                    return self
+                else:
+                    current = current.left
+            else:
+                if current.right is None:
+                    current.right = node
+                    return self
+                else:
+                    current = current.right
 
-    # Time Complexity: 
-    # Space Complexity: 
+    # Time Complexity: O(log n)
+    # Space Complexity: O(1)
     def find(self, key):
-        pass
-
-    # Time Complexity: 
-    # Space Complexity: 
+        if self.root is None:
+            return None
+        if self.root.key == key:
+            return self.root.value
+        
+        current = self.root
+        while current:
+            if key < current.key:
+                if not current.left:
+                    return None
+                elif current.left.key == key:
+                    return current.left.value
+                else:
+                    current = current.left
+            else:
+                if not current.right:
+                    return None
+                elif current.right.key == key:
+                    return current.right.value
+                else:
+                    current = current.right
+                    
+    # Time Complexity: O(n)
+    # Space Complexity: O(n)
     def inorder(self):
-        pass
+        node_list = []
+        current = self.root
+        if current == None:
+            return node_list
+        while current:
+            node_list.insert(0, {"key": current.key, "value": current.value})
+            current = current.left
+        # reset
+        current = self.root.right
+        while current:
+            node_list.append({"key": current.key, "value": current.value})
+            current = current.right
+        return node_list
+
 
-    # Time Complexity: 
-    # Space Complexity:     
+    # Time Complexity: O(n)
+    # Space Complexity: O(n)    
     def preorder(self):
-        pass
+        node_list = []
+        current = self.root
+        if current == None:
+            return node_list
+        while current:
+            node_list.append({"key": current.key, "value": current.value})
+            current = current.left
+        
+        current = self.root.right
+        while current:
+            node_list.append({"key": current.key, "value": current.value})
+            current = current.right
+        return node_list
 
-    # Time Complexity: 
-    # Space Complexity:     
+    # Time Complexity: O(n)
+    # Space Complexity: O(n)  
     def postorder(self):
-        pass
+        node_list = []
+        current = self.root
+        if current == None:
+            return node_list
+        self.postorder_helper(current, node_list)
+        return node_list
+
+    def postorder_helper(self, current, node_list): 
+        if current:
+            self.postorder_helper(current.left, node_list)
+            self.postorder_helper(current.right, node_list)
+            node_list.append({"key": current.key, "value": current.value})
+        return node_list
+
 
-    # Time Complexity: 
-    # Space Complexity:     
+    # Time Complexity: O(n)
+    # Space Complexity: O(1)     
     def height(self):
-        pass
+        current = self.root
+
+        if current is None:
+            return 0
 
+        return self.height_helper(current)
+
+    def height_helper(self, current):
+        if current is None:
+            return 0
+
+        left_height = self.height_helper(current.left)
+        right_height = self.height_helper(current.right)
+
+        return max(left_height, right_height) + 1    
+        
 
 #   # Optional Method
 #   # Time Complexity: