Here we see another solution to the 18x20 puzzle.
The structure of the solution is shown as well, in two ways.
The small figure is a reproduction of the upper left quadrant of the solution.
A representative of each type of piece is there.
(Creating such 9x10-1 configurations is a puzzle form in itself.
There are many. Note that each color conforms to Blokus rules.)
The skeletal figure, too, has one of each piece, but these are all of the same color.
The overall solution consists of four copies of either of these !
(It was constructed from the quadrants. However, if you could create a 'snake' like this, such that no two covered squares mirrored each other in any quadrant, that would be another way.) The quadrants are just rotated, reflected, and placed next to each other. The skeletons are overlaid.
The same technique was used with a different 9x10 quadrant to create a 19x19 solution. Here, only three colors were used in each quadrant, so each color only appears in three quadrants. The quadrants are 90° rotations of one another.
The same quadrant can be used to create an 18x20 solution. The appearance becomes quite dramatic when the original quadrant is reproduced in just three colors, as shown on the right.
