Solution to the puzzle Black and White.
Black and White - is one of the interesting puzzles of the Melbourne University Puzzle Hunt 2010 competition. According to the plot of the game you are pursuing a mysterious participant of a TV show trying to reveal his identity. You manage to get into the studio and then into his dressing room. There in his clothes you find a piece of paper. One side of it contains a message, the other - a conundrum and a set of instructions for it. «Decompose each of the diagrams below into 1x1, 1x2 or 1x3 strips in such a way that no grid contains strips with the same black and white pattern, even after rotation.» The puzzle consists of 25 square grids arranged in 5 rows and 5 columns. Each of these grids is divided into 25 cells by horizontal and vertical lines. The cells have a white or black background and each of them contains one letter. First, let's determine, which strips we can use to solve this problem. There are 6 different 1x3 strips (WWW, WWB, WBW, WBB, BWB and BBB), 3 different 1x