LeetCode111:Minimum Depth of Binary Tree
阿新 • • 發佈:2018-11-19
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.
Note: A leaf is a node with no children.
Example:
Given binary tree [3,9,20,null,null,15,7]
,
3 / \ 9 20 / \ 15 7
return its minimum depth = 2.
LeetCode:連結
和LeetCode104:Maximum Depth of Binary Tree要區分出來。
如果根節點為空,那麼返回0,如果左子樹為空,返回右子樹的最低高度+1,右子樹為空,返回左子樹最低高度+1,否則返回min(左子樹最低高度,右子樹最低高度)+1。
# 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 not root.left: return 1 + self.minDepth(root.right) elif not root.right: return 1 + self.minDepth(root.left) else: return 1 + min(self.minDepth(root.left), self.minDepth(root.right))