On some randomized algorithms and their evaluation

The paper considers implementations of some randomized algorithms in connection with obtaining a random $n^2\times n^2$ Sudoku matrix with programming language C++. For this purpose we describes the set ${\mathrm{\Pi }}_n$ of all $(2n)\times n$ matrices, consisting of elements of the set ${\mathbb{Z}}_n=\{1,2,\dots ,n\}$, such that every row is a permutation. We emphasize the relationship between these matrices and the $n^2\times n^2$ Sudoku matrices. An algorithm to obtain random ${\mathrm{\Pi }}_n$ matrices is presented in this paper. Several auxiliary algorithms that are related to the underlying problem have been described. We evaluated all algorithms according to two criteria - probability evaluation, and time for generation of random objects and checking of belonging to a specific set. This evaluations are interesting from both theoretical and practical point of view because they are particularly useful in the analysis of computer programs.