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