Brute-force randomized algorithm to place dominoes and try to cover as much tiles as possible. It does not try obvious placements. Instead, it places dominoes randomly, hoping that in the end all tiles will be covered (a perfect match). In case of an imperfect match, it keeps trying for up to 10k attempts, when it gives up and shows the best it could do.
Check the Wikipedia for more information about the domino tiling problem.