0 0 3 0 9 0 0 0 0 1 0 0 0 0 3 0 0 0 0 4 5 2 0 1 0 0 0 7 1 0 0 0 0 0 0 9 0 8 9 0 0 0 7 3 0 5 0 0 0 0 0 0 1 6 0 0 0 3 0 9 5 6 0 0 0 0 1 0 0 0 0 7 0 0 0 0 6 0 8 0 0 //source: http://www.sudoku-knacker.de/ (#76342, very hard)