LeetCode 108Convert Sorted Array to Binary Search Tree

题目：

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.

Subscribe to see which companies asked this question。

思路：要把升序数组 转换成（height balanced 平衡？）二叉搜索树

class TreeNode {int val;TreeNode left;TreeNode right; TreeNode(int x) {val = x;}} public class Solution {public TreeNode sortedArrayToBST(int[] num) {if (num.length == 0)return null; return sortedArrayToBST(num, 0, num.length - 1);} public TreeNode sortedArrayToBST(int[] num, int start, int end) {if (start > end)return null; int mid = (start + end) / 2;TreeNode root = new TreeNode(num[mid]);root.left = sortedArrayToBST(num, start, mid - 1);root.right = sortedArrayToBST(num, mid + 1, end); return root;}}