Q108 Convert Sorted Array to Binary Search Tree
Q108 Convert Sorted Array to Binary Search Tree
echobingo
发布于 2018-04-25 16:48:21
发布于 2018-04-25 16:48:21
Given an array where elements are sorted in ascending order, convert it to a height balanced BST.
For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.
Example:
Given the sorted array: [-10,-3,0,5,9],
One possible answer is: [0,-3,9,-10,null,5],
which represents the following height balanced BST:
0
/ \
-3 9
/ /
-10 5解题思路：
首先明白平衡二叉树的定义，注意要是每个结点必须满足。因为是将一个有序数组转化为一个平衡二叉树，因此，答案可能不唯一。
递归，将中间元素作为根节点，然后将数组分为左右两部分。左边数组用于递归创建左子树，右边数组用于递归创建右子树，直到数组为空。
Python实现：
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def sortedArrayToBST(self, num):
if not num: # 如果数组为空
return None
mid = len(num) // 2
root = TreeNode(num[mid])
root.left = self.sortedArrayToBST(num[:mid]) # 递归构建左子树
root.right = self.sortedArrayToBST(num[mid+1:]) # 递归构建右子树
return root本文参与 腾讯云自媒体分享计划，分享自作者个人站点/博客。
原始发表：2018.02.28 ，如有侵权请联系 cloudcommunity@tencent.com 删除
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