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
# 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 1 _left = min(self.minDepth(root.left),10000) _right = min(self.minDepth(root.right),10000) if (root.left == None or root.right == None): return _left +_right+1 return min(_left,_right)+1