230. Kth Smallest Element in a BST

class Solution {

    public void inorder(TreeNode root ,ArrayList<Integer>list ){
        if(root != null){
            inorder(root.left,list);
            list.add(root.val);
            inorder(root.right,list);
        }
    }
    public int kthSmallest(TreeNode root, int k) {
        ArrayList<Integer>list = new ArrayList<>();
        inorder(root,list);
        if(list.size() == 0){
            return 0;
        }
        System.out.print(Arrays.asList(list));
        return list.get(k-1);
    }
}