I really like this task. It's was fun. My code gave right answer for first 2 boards. But for board 3 it gave 18 instead of 20.
I have no idea why. Those are the logs(Zeroes are empty places). Can somebody point me in the right direction?

[ [ 1, 2, 0, 0, 0, 0, 0, 0, 0, 'Z 18' ]
[ 3, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 2, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 1, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 3, 0, 0, 0, 0, 0, 0, 0, 0, 0 ] ]

[ [ 1, 2, 0, 0, 0, 0, 0, 0, 'Z 12', 0 ],
[ 3, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 2, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 1, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 3, 0, 0, 0, 0, 0, 0, 0, 0, 0 ] ]

[ [ 1, 2, 0, 0, 0, 0, 0, 'Z 9', 0, 0 ],
[ 3, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 2, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 1, 'S', 0, 0, 0, 0, 0, 0, 0, 'Z 10' ],
[ 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 3, 0, 0, 0, 0, 0, 0, 0, 0, 'Z 22' ] ]\

[ [ 1, 2, 0, 0, 0, 0, 'Z 6', 0, 0, 0 ],
[ 3, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 2, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 1, 'S', 0, 0, 0, 0, 0, 0, 'Z 8', 0 ],
[ 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 3, 0, 0, 0, 0, 0, 0, 0, 'Z 19', 0 ] ]

[ [ 1, 2, 0, 0, 0, 'Z 3', 0, 0, 0, 0 ],
[ 3, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 2, 'S', 0, 0, 0, 0, 0, 0, 0, 'Z 18' ],
[ 1, 'S', 0, 0, 0, 0, 0, 'Z 6', 0, 0 ],
[ 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 3, 0, 0, 0, 0, 0, 0, 'Z 16', 0, 0 ] ]

[ [ 1, 2, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 3, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 2, 'S', 0, 0, 0, 0, 0, 0, 'Z 15', 0 ],
[ 1, 'S', 0, 0, 0, 0, 'Z 4', 0, 0, 0 ],
[ 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 3, 0, 0, 0, 0, 0, 'Z 13', 0, 0, 0 ] ]

[ [ 1, 2, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 3, 'S', 0, 0, 0, 0, 0, 0, 0, 'Z 31' ],
[ 2, 'S', 0, 0, 0, 0, 0, 'Z 12', 0, 0 ],
[ 1, 'S', 0, 0, 0, 'Z 2', 0, 0, 0, 0 ],
[ 2, 0, 0, 0, 0, 0, 0, 0, 0, 'Z 7' ],
[ 3, 0, 0, 0, 0, 'Z 9', 0, 0, 0, 0 ] ]

[ [ 1, 2, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 3, 'S', 0, 0, 0, 0, 0, 0, 'Z 27', 0 ],
[ 2, 'S', 0, 0, 0, 0, 'Z 9', 0, 0, 0 ],
[ 1, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 2, 0, 0, 0, 0, 0, 0, 0, 'Z 5', 0 ],
[ 3, 0, 0, 0, 'Z 5', 0, 0, 0, 0, 0 ] ]

[ [ 1, 2, 0, 0, 0, 0, 0, 0, 0, 'Z 19' ],
[ 3, 'S', 0, 0, 0, 0, 0, 'Z 23', 0, 'Z 8' ],
[ 2, 'S', 0, 0, 0, 'Z 6', 0, 0, 0, 'Z 17' ],
[ 1, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 2, 0, 0, 0, 0, 0, 0, 'Z 3', 0, 0 ],
[ 3, 0, 0, 'Z 1', 0, 0, 0, 0, 0, 0 ] ]

[ [ 1, 2, 0, 0, 0, 0, 0, 0, 'Z 16', 0 ],
[ 3, 'S', 0, 0, 0, 0, 'Z 19', 0, 'Z 8', 0 ],
[ 2, 'S', 0, 0, 'Z 3', 0, 0, 0, 'Z 17', 0 ],
[ 1, 'S', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 2, 0, 0, 0, 0, 0, 'Z 1', 0, 0, 0 ],
[ 3, 0, 0, 0, 0, 0, 0, 0, 0, 0 ] ]

[ [ 1, 2, 0, 0, 0, 0, 0, 'Z 13', 0, 0 ],
[ 3, 'S', 0, 0, 0, 'Z 15', 0, 'Z 8', 0, 0 ],
[ 2, 'S', 0, 0, 0, 0, 0, 'Z 17', 0, 0 ],
[ 1, 'S', 0, 0, 0, 0, 0, 0, 0, 'Z 16' ],
[ 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 3, 0, 0, 0, 0, 0, 0, 0, 0, 0 ] ]

[ [ 1, 2, 0, 0, 0, 0, 'Z 10', 0, 0, 'Z 15' ],
[ 3, 'S', 0, 0, 'Z 11', 0, 'Z 8', 0, 0, 0 ],
[ 2, 'S', 0, 0, 0, 0, 'Z 14', 0, 0, 0 ],
[ 1, 'S', 0, 0, 0, 0, 0, 0, 'Z 14', 0 ],
[ 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 3, 0, 0, 0, 0, 0, 0, 0, 0, 0 ] ]

[ [ 1, 2, 0, 0, 0, 'Z 7', 0, 0, 'Z 15', 0 ],
[ 3, 'S', 0, 'Z 6', 0, 'Z 8', 0, 0, 0, 0 ],
[ 2, 'S', 0, 0, 0, 'Z 11', 0, 0, 0, 0 ],
[ 1, 'S', 0, 0, 0, 0, 0, 'Z 12', 0, 0 ],
[ 2, 0, 0, 0, 0, 0, 0, 0, 0, 'Z 19' ],
[ 3, 0, 0, 0, 0, 0, 0, 0, 0, 0 ] ]

[ [ 1, 2, 0, 0, 'Z 3', 0, 0, 'Z 15', 0, 0 ],
[ 3, 'S', 'Z 1', 0, 'Z 8', 0, 0, 0, 0, 0 ],
[ 2, 'S', 0, 0, 'Z 8', 0, 0, 0, 0, 0 ],
[ 1, 'S', 0, 0, 0, 0, 'Z 10', 0, 0, 0 ],
[ 2, 0, 0, 0, 0, 0, 0, 0, 'Z 17', 0 ],
[ 3, 0, 0, 0, 0, 0, 0, 0, 0, 0 ] ]

[ [ 1, 2, 0, 0, 0, 0, 'Z 15', 0, 0, 0 ],
[ 3, 0, 0, 'Z 6', 0, 0, 0, 0, 0, 0 ],
[ 2, 0, 0, 'Z 6', 0, 0, 0, 0, 0, 0 ],
[ 1, 0, 0, 0, 0, 'Z 9', 0, 0, 0, 0 ],
[ 2, 0, 0, 0, 0, 0, 0, 'Z 15', 0, 0 ],
[ 3, 0, 0, 0, 0, 0, 0, 0, 0, 0 ] ]

[ [ 1, 2, 0, 0, 0, 'Z 12', 0, 0, 0, 0 ],
[ 3, 0, 'Z 3', 0, 0, 0, 0, 0, 0, 0 ],
[ 2, 0, 'Z 4', 0, 0, 0, 0, 0, 0, 0 ],
[ 1, 0, 0, 0, 'Z 8', 0, 0, 0, 0, 0 ],
[ 2, 0, 0, 0, 0, 0, 'Z 13', 0, 0, 0 ],
[ 3, 0, 0, 0, 0, 0, 0, 0, 0, 0 ] ]

[ [ 1, 2, 0, 0, 'Z 9', 0, 0, 0, 0, 0 ],
[ 3, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 2, 'Z 2', 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 1, 0, 0, 'Z 7', 0, 0, 0, 0, 0, 0 ],
[ 2, 0, 0, 0, 0, 'Z 11', 0, 0, 0, 0 ],
[ 3, 0, 0, 0, 0, 0, 0, 0, 0, 0 ] ]

[ [ 1, 2, 0, 'Z 6', 0, 0, 0, 0, 0, 0 ],
[ 3, 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 'Z 2', 0, 0, 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 'Z 7', 0, 0, 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 'Z 11', 0, 0, 0, 0, 0 ],
[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ] ]

The way my solution "works" is so scuffed now that I look at Your work.Thank You for Your explanations how it works.