Can a distributed algorithm be serial?
Distributed algorithms are sub-type of parallel algorithm. Different parts of algorithm executes simultaneously on different processors with minimum information sharing and minimum dependency among them. Although the difference between parallel algorithm and distributed algorithm is not very clear but in general parallel algorithm is used for speed-up and increase data handling capacity while distributed algorithm is mainly implemented for fault tolerance, scalability. But in your case, may be you are just storing data in different places (distributed) but the algorithm you are using is not a distributed algorithm.