Sudoku solver

Summary

The script sudoku-solver.py solves Sudoku puzzles.

Prerequisites

• mise

mise exec -- pixi shell

Usage

./sudoku-solver.py --help

usage: sudoku-solver.py [-h] [--output-dir OUTPUT_DIR] [--sep SEP] [--solution-limit SOLUTION_LIMIT] INPUT_FILE

positional arguments:
  INPUT_FILE            Sudoku puzzle will be read from this file

options:
  -h, --help            show this help message and exit
  --output-dir OUTPUT_DIR
                        Sudoku puzzle solutions will be written to this directory (default: output)
  --sep SEP             separator delimiting values within a row (input and output) (default: ,)
  --solution-limit SOLUTION_LIMIT
                        limit the number of solutions to this value (0 for no limit) (default: 1)

Examples

Feasible

cat -- feasible.csv

5,3,,,7,,,,
6,,,1,9,5,,,
,9,8,,,,,6,
8,,,,6,,,,3
4,,,8,,3,,,1
7,,,,2,,,,6
,6,,,,,2,8,
,,,4,1,9,,,5
,,,,8,,,7,9

./sudoku-solver.py -- feasible.csv

Status:          OPTIMAL
Solutions found: 1
Wall time:       0.001425
Branches:        0
Conflicts:       0

column -t -s , -- output/0.csv

5  3  4  6  7  8  9  1  2
6  7  2  1  9  5  3  4  8
1  9  8  3  4  2  5  6  7
8  5  9  7  6  1  4  2  3
4  2  6  8  5  3  7  9  1
7  1  3  9  2  4  8  5  6
9  6  1  5  3  7  2  8  4
2  8  7  4  1  9  6  3  5
3  4  5  2  8  6  1  7  9

Infeasible

cat -- infeasible.csv

8,3,,,7,,,,
6,,,1,9,5,,,
,9,8,,,,,6,
8,,,,6,,,,3
4,,,8,,3,,,1
7,,,,2,,,,6
,6,,,,,2,8,
,,,4,1,9,,,5
,,,,8,,,7,9

./sudoku-solver.py -- infeasible.csv

Status:          INFEASIBLE
Solutions found: 0
Wall time:       0.000146
Branches:        0
Conflicts:       0

Blank 4x4

cat -- blank-4x4.csv

,,,
,,,
,,,
,,,

./sudoku-solver.py --solution-limit 0 -- blank-4x4.csv

Status:          OPTIMAL
Solutions found: 288
Wall time:       0.034108
Branches:        3571
Conflicts:       35

ls -1b -- output/*.csv | wc -l
# 288