Solving Every Sudoku Puzzle

To learn the Go language, I setup one topic, Sudoku solver, as my first homework. After Googling, I found Dimitri's sudoku github project, https://github.com/dimitri/sudoku, and learned Peter Norvig's Python implementation in http://norvig.com/sudoku.html.

Sudoku Notation and Preliminary Notions by copying from Dimitri

First we have to agree on some notation. A Sudoku puzzle is a grid of 81 squares; the majority of enthusiasts label the columns 1-9, the rows A-I, and call a collection of nine squares (column, row, or box) a unit and the squares that share a unit the peers. A puzzle leaves some squares blank and fills others with digits, and the whole idea is:

A puzzle is solved if the squares in each unit are filled with a permutation of the digits 1 to 9.

Performances

Original Python version

With Dimitri's modification and port to Python 3 on my PC,

C:\> sudoku.dim.py
All tests pass.
Solved 50 of 50 easy puzzles (avg 0.01 secs (199 Hz), max 0.01 secs).
Solved 95 of 95 hard puzzles (avg 0.02 secs (51 Hz), max 0.10 secs).
Solved 11 of 11 hardest puzzles (avg 0.01 secs (143 Hz), max 0.01 secs).
Solved 99 of 99 random puzzles (avg 0.01 secs (177 Hz), max 0.01 secs).

Golang version

The performance result of my first version(RELEASE_0.9.0), using the slices and maps of strings as Python with the same notation as Peter Norvig.

BenchmarkSolveAll/easy-4                      50           1921266 ns/op    (520Hz)
BenchmarkSolveAll/hard-4                      95           8290041 ns/op    (120Hz)
BenchmarkSolveAll/hardest-4                   11           2728909 ns/op    (366Hz)

BenchmarkSolveHardest/Hard01-4                 1        26523877800 ns/op   (26.5 secs)

The benchmark(RELEASE_0.9.6) with changing maps to one dimension slices, it enhanced about 2.7+ times

BenchmarkSolveAll/easy-4                      50            680506 ns/op    (1469Hz / 2.8x)
BenchmarkSolveAll/hard-4                      95           2327876 ns/op    (429Hz / 3.5x)
BenchmarkSolveAll/hardest-4                   11           1000763 ns/op    (999Hz / 2.7x)

BenchmarkSolveHardest/Hard01-4                 1        6983976900 ns/op    (6.98 secs / 3.8x)

Build and Test

Sample shell commands to run the tests and benchmarks of the Go package, sudoku.

   cd _Some_Folder_\sudoku\pkg\sudoku
   go build
   go test
   go test -bench SolveAll

Sample shell commands to run the sudoku application

   cd _Some_Folder_\sudoku
   go run main.go .....1...87.9..6..1.....9.3..16.8.3.........6..63.4.......5......4.2..98.59..7.21
   go run main.go -help
   go run main.go

To-Do

• Studying Go Modules to learn how to deploy Go application with versions and fixed assets.
  • https://github.com/golang/go/wiki/Modules