Update 236.lowest-common-ancestor-of-a-binary-tree.md

Author: taojin1992

problems/236.lowest-common-ancestor-of-a-binary-tree.md

@@ -138,7 +138,7 @@ class Solution:
 **复杂度分析**
 
 - 时间复杂度：$O(N)$
-- 空间复杂度：$O(N)$
+- 空间复杂度：$O(Height)$
 
 ## 扩展