Untitled

class Solution {
    TreeNode cur;
    public TreeNode increasingBST(TreeNode root) {
        TreeNode dummy = new TreeNode(0);
        cur = dummy;
        inorder(root);
        return dummy.right;
    }

    public void inorder(TreeNode node) {
        if (node == null) return;
        inorder(node.left);
        node.left = null;
        cur.right = node;
        cur = node;
        inorder(node.right);
    }
}