Leetcode 1008 - study Java code

Leetcode1008_ConstructBSTFromPreOrder.java

// https://leetcode.com/problems/construct-binary-search-tree-from-preorder-traversal/discuss/252479/Simple-Recursive-solution-in-Java-(more-verbose)
public TreeNode bstFromPreorder(int[] preorder) {
        return bstFromPreorder(preorder, 0, preorder.length - 1);
    }
    
    public TreeNode bstFromPreorder(int[] order, int start, int end) {
        if (start > end) {
            return null;
        }
        TreeNode node = new TreeNode(order[start]);
        int rightStart = start;
        for (int i = start; i <= end; i++) {
            if (order[start] < order[i]) {
                break;
            }
            rightStart = i;
        }
        node.left = bstFromPreorder(order, start + 1, rightStart);
        node.right = bstFromPreorder(order, rightStart + 1, end);
        return node;
    }