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111.二叉树的最小深度.py
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111.二叉树的最小深度.py
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#
# @lc app=leetcode.cn id=111 lang=python3
#
# [111] 二叉树的最小深度
#
# https://leetcode-cn.com/problems/minimum-depth-of-binary-tree/description/
#
# algorithms
# Easy (41.63%)
# Likes: 218
# Dislikes: 0
# Total Accepted: 55.1K
# Total Submissions: 132.2K
# Testcase Example: '[3,9,20,null,null,15,7]'
#
# 给定一个二叉树,找出其最小深度。
#
# 最小深度是从根节点到最近叶子节点的最短路径上的节点数量。
#
# 说明: 叶子节点是指没有子节点的节点。
#
# 示例:
#
# 给定二叉树 [3,9,20,null,null,15,7],
#
# 3
# / \
# 9 20
# / \
# 15 7
#
# 返回它的最小深度 2.
#
#
# **BFS&DFS**
# @lc code=start
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def minDepth(self, root: TreeNode) -> int:
if not root: return 0
if not root.left: return 1 + self.minDepth(root.right)
if not root.right: return 1 + self.minDepth(root.left)
return 1 + min(self.minDepth(root.right), self.minDepth(root.left))
# @lc code=end