[LeetCode]题解（python）：111 Minimum Depth of Binary Tree

题目来源

---

https://leetcode.com/problems/minimum-depth-of-binary-tree/

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.

---

题意分析

---

Input: a binary tree

Output: leaf node 的最小深度

Conditions: 注意一定要是leaf节点，求leaf节点的最小深度

---

题目思路

---

递归，注意与求最大深度不同

---

AC代码（Python）

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

 class Solution(object):
     def minDepth(self, root):
         """
         :type root: TreeNode
         :rtype: int
         """
         if root == None:
             return 0
         if root.left == None and root.right != None:
             return self.minDepth(root.right) + 1
         if root.left != None and root.right == None:
             return self.minDepth(root.left) + 1
         return min(self.minDepth(root.left), self.minDepth(root.right)) + 1