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：

[code]        int mid = (start + end) / 2;
        TreeNode root = new TreeNode(nums[mid]);

        root.left = buildBST(start, mid);
        root.right = buildBST(mid + 1, end);

代码

[code]    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;
    }