public boolean isSameTree(TreeNode p, TreeNode q) {//passed without even testing on eclipse!
        if (p == null && q == null) {
            return true;
        }
        else if (p == null && q != null) {
            return false;
        }
        else if (p != null && q == null) {
            return false;
        }
        else {
            if ((p.val == q.val) &&
                    isSameTree(p.left, q.left) &&
                    isSameTree(p.right, q.right))
                return true;
            else return false;
        }
    }