//Recursive solution: avoid copy array
//Time: O(n), 7ms
//Space: O(h)
class Solution {
    public TreeNode constructMaximumBinaryTree(int[] nums) {
        return constructR(nums, 0, nums.length);
    }

    private TreeNode constructR(int[] nums, int begin, int end) {
        if(begin >= end) return null;
        int max = begin;
        for(int i = begin; i < end; i++) {
            if(nums[i] > nums[max]) {
                max = i;
            }
        }
        TreeNode root = new TreeNode(nums[max]);
        root.left = constructR(nums, begin, max);
        root.right = constructR(nums, max + 1, end);
        return root;
    }
}
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */