class Solution {
    public TreeNode pruneTree(TreeNode root) {
        if (root == null) {
            return root;
        }

        root.left = pruneTree(root.left);
        root.right = pruneTree(root.right);

        if (root.val == 1 || root.left != null || root.right != null) {
            return root;
        }

        return null;

    }
}