LeetCode SameTree

public boolean isSameTree(TreeNode p, TreeNode q) {
        if (p==null && q == null) return true;
        if (p==null || q == null) return false;
        if (q.val != p.val) return false;
        else return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
    }