  In this article, we discuss the implementation of a quantum recommendation
system that uses a quantum variant of the k-nearest neighbours algorithm and
the Grover algorithm to search for a specific element in unstructured database.
In addition to the presentation of the recommendation system as an algorithm,
the article also shows a main steps in construction of a suitable quantum
circuit for realisation of a given recommendation system. The computational
complexity of individual calculation steps during recommendation system was
also indicated. The verification correctness of a proposed recommendation
system was also analysed, indicating an algebraic equation describing the
probability of success of the recommendation. The article also shows numerical
examples presenting the behaviour of the recommendation system for two selected
cases.
