1. 题目

2. 思路

(1) 递归

• 取数组中间元素作为根结点，递归生成根结点的左右子树即可。

3. 代码

public class Test {
    
    
    public static void main(String[] args) {
    
    
    }
}

class TreeNode {
    
    
    int val;
    TreeNode left;
    TreeNode right;

    TreeNode() {
    
    
    }

    TreeNode(int val) {
    
    
        this.val = val;
    }

    TreeNode(int val, TreeNode left, TreeNode right) {
    
    
        this.val = val;
        this.left = left;
        this.right = right;
    }
}

class Solution {
    
    
    public TreeNode sortedArrayToBST(int[] nums) {
    
    
        return recur(nums, 0, nums.length - 1);
    }

    private TreeNode recur(int[] nums, int left, int right) {
    
    
        if (left > right) {
    
    
            return null;
        }
        int mid = left + ((right - left) >> 1);
        TreeNode root = new TreeNode(nums[mid]);
        root.left = recur(nums, left, mid - 1);
        root.right = recur(nums, mid + 1, right);
        return root;
    }
}