【Leetcode】108. 将有序数组转换为二叉搜索树

      0
     / \
   -3   9
   /   /
 -10  5

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

    public TreeNode helper(int[] nums, int left, int right) {
        if (left > right) {
            return null;
        }

        if (left == right) {
            return new TreeNode(nums[left]);
        }

        int mid = (left + right) / 2;
        TreeNode current = new TreeNode(nums[mid]);
        current.left = helper(nums, left, mid - 1);
        current.right = helper(nums, mid + 1, right);
        return current;
    }
}