Generates random Sudoku instances using time-bounded search and a combination of heuristics. The resulting instances contain very few hints, down to around 20. Note that no Sudoku instance with less than 17 hints has a unique solution, and 20 is pretty close to that.
The codebase also contains utilities to guarantee a fixed number of hints, and you can even supply your own heuristics!
Here are 10 puzzle instances where the generator was allowed to take 0.1 seconds per instance.
Each line contains a separate instance, row by row, where 0 denotes an empty field.
You can solve these instances using my own solver, or you can write your own!
005000000060800000403019800000002000102400006000068007000300000500090010001200390
000003004580240000000600008002400060950000800030006000000010670007000000800034050
900400000070009200002050038001004007040000003025030000000208040000070001050000000
000005006000040009000100572070000000000304000198070000600000380003400700050009060
005001070300064500064000000000280000000010084080900000008000100500000090007630008
700090200050060300080000005000900500003400010100000070300000004000107000090280000
026000000300800006014000079000080010009200600000700004500901000900000040000002080
056040020094507008000100000002003000900060300000800500500000040007000600040000005
000700000003000850704601000000010000006009040050083600200000900091007000000000021
030000500000004000061090020000100003080000006300800000004030001100000070500609004