Tree - 108. Convert Sorted Array to Binary Search Tree Easy
Tree - 108. Convert Sorted Array to Binary Search Tree Easy
ppxai
发布于 2020-09-23 17:28:53
发布于 2020-09-23 17:28:53
108. Convert Sorted Array to Binary Search Tree
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思路：
将有序数组变成bst，做法就是取出数组中的中位数当root节点，然后将root节点两边分别递归求bst，注意这里的中位数，如果是偶数个数组是向上取整，即
[0, 1, 7, 8]的root是7,下标为2。
代码：
go：
/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
func sortedArrayToBST(nums []int) *TreeNode {
if nums == nil || len(nums) == 0 {
return nil
}
return recursion(nums, 0, len(nums))
}
func recursion(nums []int, low int, high int) *TreeNode {
if low >= high { // leaf
return nil
}
mid := (high-low)/2 + low
return &TreeNode{
Val: nums[mid],
Left: recursion(nums, low, mid),
Right: recursion(nums, mid+1, high)}
}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：2019年08月28日，如有侵权请联系 cloudcommunity@tencent.com 删除
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