Update 79. 合并二叉树.md

Author: jasoncao11

79. 合并二叉树.md

@@ -1,4 +1,4 @@
-![algo31](./images/algo31.jpg)
+![algo31](./images/algo31.png)
 
 ```
 # Definition for a binary tree node.
@@ -24,4 +24,4 @@ class Solution(object):
         merged.left = self.mergeTrees(root1.left, root2.left)
         merged.right = self.mergeTrees(root1.right, root2.right)
         return merged 
-```
+```