Convert Sorted Array to Binary Search Tree

描述

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

题解

package algorithms

import "github.com/ljun20160606/leetcode/algorithms"

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */

type TreeNode = algorithms.TreeNode

func sortedArrayToBST(nums []int) *TreeNode {
	if len(nums) == 0 {
		return nil
	}

	mid := len(nums) / 2
	return &TreeNode{
		Val:   nums[mid],
		Left:  sortedArrayToBST(nums[:mid]),
		Right: sortedArrayToBST(nums[mid+1:]),
	}
}