diff --git a/binary_search_tree/tree.py b/binary_search_tree/tree.py
index cdd5abc..799f91f 100644
--- a/binary_search_tree/tree.py
+++ b/binary_search_tree/tree.py
@@ -1,3 +1,6 @@
+from queue import Queue
+
+
 class TreeNode:
     def __init__(self, key, val = None):
         if val == None:
@@ -14,42 +17,117 @@ class Tree:
     def __init__(self):
         self.root = None
 
-    # Time Complexity: 
-    # Space Complexity: 
+    # Time Complexity: O(log(n))
+    # Space Complexity: O(1) 
     def add(self, key, value = None):
-        pass
+        def add_helper(node, key, value = None):
+            if key < node.key:
+                if node.left is None:
+                    node.left = TreeNode(key, value)
+                    return
+                else:
+                    add_helper(node.left, key, value)
+                    return
+            if key > node.key:
+                if node.right is None:
+                    node.right = TreeNode(key, value)
+                    return
+                else:
+                    add_helper(node.right, key, value)
+                    return
+
+        if self.root is None:
+            self.root = TreeNode(key, value)
+            return
+        add_helper(self.root, key, value)
 
-    # Time Complexity: 
-    # Space Complexity: 
+    # Time Complexity: O(log(n)) 
+    # Space Complexity: O(log(n)) 
     def find(self, key):
-        pass
+        def find_helper(node, key):
+            if node is None:
+                return None
+            elif node.key == key:
+                return node.value
+            elif key < node.key:
+                return find_helper(node.left, key)
+            elif key > node.key:
+                return find_helper(node.right, key)
 
-    # Time Complexity: 
-    # Space Complexity: 
+        return find_helper(self.root, key)
+
+    # Time Complexity: O(n) 
+    # Space Complexity: O(n) 
     def inorder(self):
-        pass
+        def inorder_helper(inorder_list, node):
+            if node is None:
+                return
+            inorder_helper(inorder_list, node.left)
+            inorder_list.append({"key": node.key, "value": node.value})
+            inorder_helper(inorder_list, node.right)
+
+        inorder_list = []
+        inorder_helper(inorder_list, self.root)
+        return inorder_list
 
-    # Time Complexity: 
-    # Space Complexity:     
+    # Time Complexity: O(n) 
+    # Space Complexity: O(n) 
     def preorder(self):
-        pass
+        def preorder_helper(inorder_list, node):
+            if node is None:
+                return
+            preorder_list.append({"key": node.key, "value": node.value})
+            preorder_helper(inorder_list, node.left)
+            preorder_helper(inorder_list, node.right)
 
-    # Time Complexity: 
-    # Space Complexity:     
+        preorder_list = []
+        preorder_helper(preorder_list, self.root)
+        return preorder_list
+
+    # Time Complexity: O(n) 
+    # Space Complexity: O(n) 
     def postorder(self):
-        pass
+        def postorder_helper(inorder_list, node):
+            if node is None:
+                return
+            postorder_helper(inorder_list, node.left)
+            postorder_helper(inorder_list, node.right)
+            postorder_list.append({"key": node.key, "value": node.value})
+
+        postorder_list = []
+        postorder_helper(postorder_list, self.root)
+        return postorder_list
 
-    # Time Complexity: 
-    # Space Complexity:     
+    # Time Complexity: O(n) 
+    # Space Complexity: O(n) 
     def height(self):
-        pass
+        def height_helper(node):
+            if node is None:
+                return 0
+            return 1 + max(height_helper(node.left), height_helper(node.right))
+        return height_helper(self.root) 
 
 
 #   # Optional Method
-#   # Time Complexity: 
-#   # Space Complexity: 
+    # Time Complexity: O(n) 
+    # Space Complexity: O(n) 
     def bfs(self):
-        pass
+        if self.root is None:
+            return []
+
+
+        bfs_result = []
+        bfs_queue = Queue()
+        bfs_queue.put(self.root)
+        while not bfs_queue.empty():
+            node = bfs_queue.get()
+            bfs_result.append({"key": node.key, "value": node.value})
+            if node.left is not None:
+                bfs_queue.put(node.left)
+            if node.right is not None:
+                bfs_queue.put(node.right)
+
+        return bfs_result