diff --git a/Tree/MaximumDepthOfBinaryTree.swift b/Tree/MaximumDepthOfBinaryTree.swift
index c85f713..20f48f1 100644
--- a/Tree/MaximumDepthOfBinaryTree.swift
+++ b/Tree/MaximumDepthOfBinaryTree.swift
@@ -1,7 +1,7 @@
 /**
  * Question Link: https://leetcode.com/problems/maximum-depth-of-binary-tree/
  * Primary idea: recursion, return 0 when it is a leaf node
- * Time Complexity: O(n), Space Complexity: O(1)
+ * Time Complexity: O(n), Space Complexity: O(n)
  * 
  * Definition for a binary tree node.
  * public class TreeNode {
@@ -24,4 +24,4 @@ class MaximumDepthOfBinaryTree {
         
         return max(maxDepth(root.left), maxDepth(root.right)) + 1
     }
-}
\ No newline at end of file
+}
diff --git a/Untitled Diagram.drawio b/Untitled Diagram.drawio
new file mode 100644
index 0000000..8be4b73
--- /dev/null
+++ b/Untitled Diagram.drawio	
@@ -0,0 +1 @@
+<mxfile host="app.diagrams.net" modified="2021-06-26T10:30:36.251Z" agent="5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0.2 Safari/605.1.15" version="14.8.1" etag="C7cKlcd7peqngDCRmi4K" type="github"><diagram id="pOEUxFl0UyUz3P6jQt2X">UzV2zq1wL0osyPDNT0nNUTV2VTV2LsrPL4GwciucU3NyVI0MMlNUjV1UjYwMgFjVyA2HrCFY1qAgsSg1rwSLBiADYTaQg2Y1AA==</diagram></mxfile>
\ No newline at end of file