Sudoku is a logic game which has recently gained a wide popularity. The game operates thusly: using numbers 1 through 9, you must fill in a nine-column, nine-row grid (made of 9 3x3 blocks) without repeating digits. All the digits between 1 and 9 must be present once and only once in each row, each column and each block.
- naked quadruplets reduction.
- hidden quadruplets reduction.
- swordfish reduction.
- new option -e to put in explanatory mode.
- new option -i to ignore some solving techniques.
- new option -l to rate the level of difficulty.
- support for pipes: sudokut can now read from standard input.
- improved readability of messages.