【leetcode】Minimum Depth of Binary Tree

题目简述：

Given a binary tree, find its minimum depth.

The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.

解题思路：

# Definition for a  binary tree node
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
# @param root, a tree node
# @return an integer
min = 99999
def minDeep(self, root, cur):
if root == None:
self.min = 0
return
cur += 1
if root.left == None and root.right ==None:
if self.min >cur:
self.min = cur
return

if root.left != None:
self.minDeep(root.left, cur)
if root.right != None:
self.minDeep(root.right, cur)

def minDepth(self, root):
self.minDeep(root, 0)
return self.min