1 # Definition for a  binary tree node
 2 # class TreeNode:
 3 #     def __init__(self, x):
 4 #         self.val = x
 5 #         self.left = None
 6 #         self.right = None
 7 
 8 class Solution:
 9     # @param root, a tree node
10     # @return an integer
11     def minDepth(self, root):
12         if root == None:
13             return 0
14         if root.left==None and root.right==None:
15             return 1
16         l,r = 9999,9999
17         if root.left!=None:
18             l = self.minDepth(root.left)
19         if root.right!=None:
20             r = self.minDepth(root.right)
21         if l<r:
22             return 1+l
23         return 1+r