LeetCode 108 Convert Sorted Array to Binary Search Tree

题目描述

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

分析

参考：LeetCode 105 Construct Binary Tree from Preorder and Inorder Traversal

只是根结点为mid，核心代码如下：

        int mid = (start + end) / 2;        TreeNode root = new TreeNode(nums[mid]);        root.left = buildBST(start, mid);        root.right = buildBST(mid + 1, end);

代码

    int[] nums;    public TreeNode sortedArrayToBST(int[] nums) {        this.nums = nums;        return buildBST(0, nums.length);    }    TreeNode buildBST(int start, int end) {        if (start >= end) {            return null;        }        int mid = (start + end) / 2;        TreeNode root = new TreeNode(nums[mid]);        root.left = buildBST(start, mid);        root.right = buildBST(mid + 1, end);        return root;    }