ref: fbd35e617d53c4ad50a44f85c2bd9d31928eddd1
dir: /sys/games/lib/sudoku/boards/hard000.su/
36..2..89 ...361... ......... 8.3...6.2 4..6.3..7 6.7...1.8 ......... ...418... 97..3..14 361524789 789361425 524879361 893157642 412683597 657942138 148796253 235418976 976235814