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

题目来源

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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.

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题意分析

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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

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题目思路

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递归，注意与求最大深度不同

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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