Rate difficulty of Sudoku by applying strategies as a human would in order to solve it
The solver attempts to solve a given Sudoku iteratively, applying strategies from easiest to most difficult.
If a strategy is successful, the affected candidates are removed or the cells are filled with the resulting digits. The number of affected candidates/cells is added to a running total, as is the difficulty level of the respective strategy.
After solving the Sudoku, the total difficulty is divided by the sum of the affected candidates and cells, which provides a good estimate of the perceived difficulty (effort). The higher the value, the more difficult the Sudoku typically is for a human. This software uses the same effort values as HoDoKu.
The following strategies are currently (about to be) implemented:
| Code | Test | OK | Strategy | Effort |
|---|---|---|---|---|
| ☒ | ☒ | ☒ | Last Digit | 4 |
| ☒ | ☒ | ☒ | Obvious Single | 5 |
| ☒ | ☒ | ☒ | Hidden Single | 14 |
| ☒ | ☒ | ☒ | Locked Pair | 40 |
| ☒ | ☒ | ☒ | Pointing Pair | 50 |
| ☒ | ☒ | ☒ | Claiming Pair | 50 |
| ☒ | ☒ | ☒ | Obvious Pair | 60 |
| ☒ | ☒ | ☒ | Hidden Pair | 70 |
| ☒ | ☒ | ☒ | Naked Triplet | 80 |
| ☒ | ☐ | ☐ | Skyscraper | 130 |
| ☒ | ☒ | ☒ | X-Wing | 140 |
More to come …
Generate Sudokus with 19 filled cells and append them to the file generated/19.txt
cargo run --bin gen --release -- -n 19 >> generated/19.txt
Get help on generator with:
cargo run --bin gen --release -- --help
cargo run --bin sudokui --release
You can paste Sudoku puzzles with Ctrl+V (Cmd+V on Mac) in single-line format like
405030809000000007200004030100000006000050400000001003000600024070900000890000000 or
in matrix format like
4 0 5 0 3 0 8 0 9
0 0 0 0 0 0 0 0 7
2 0 0 0 0 4 0 3 0
1 0 0 0 0 0 0 0 6
0 0 0 0 5 0 4 0 0
0 0 0 0 0 1 0 0 3
0 0 0 6 0 0 0 2 4
0 7 0 9 0 0 0 0 0
8 9 0 0 0 0 0 0 0
"File/Save as ..." allows you to save the current state (filled cells and candidates) of the puzzle in multiple formats. With the suffix ".zst" a binary, zstd compressed file is written. ".bin" represents such a binary without compression. If you need a human-readable representation use the suffix ".json" which leads to a file in JSON format. With "File/Load" you can load each of these files.
Rate the Sudoku
0 7 0 0 0 5 0 0 0
0 0 0 0 0 6 0 1 0
0 0 3 0 0 7 6 2 8
0 0 0 1 6 0 0 0 0
1 0 0 5 0 0 8 0 0
0 0 6 0 0 4 2 0 0
0 9 4 0 3 1 0 0 0
0 0 0 0 0 0 4 0 0
0 2 0 6 0 0 0 0 0
with
cargo run --bin rate --release -- 070005000000000010003007628000160000100500800006004200094031000000000400020600000