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* wip sudoku engine; still buggy for expert puzzle * engine update; still buggy expert mode * better expert support with re-attempts after 3 sec
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| # Dependency directories (remove the comment below to include it) | ||
| # vendor/ | ||
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| sku | ||
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| @@ -1 +1 @@ | ||
| r5.a81afe3 | ||
| r6.971f844 |
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| # Sudoku Engine | ||
| This package is a **non** efficient implementation of a sudoku solver and generator. It is ~~stolen~~ ported from [this python implementation](https://www.101computing.net/sudoku-generator-algorithm/), all credits go to the author. It is a simple recursive and backtracking engine, easy to understand and read. | ||
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| ## Motivation | ||
| This minimal implementation was done due to the lack of a package that simply has the two sensible features needed by a sudoku engine: | ||
| 1. can both solve & generate | ||
| 2. do generate a one-solution puzzle | ||
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| without useless features or generally cumbersome development experience (e.g. overly complicated structures, interfaces, initialization methods, etc). | ||
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| If you need the aforementioned features this package is not the right one, since it only does point 1 and 2. | ||
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| If you need a super efficient implementation this package is not the right one since it is aimed to be simple at the expense of speed; if you need something like that you can use/write one that leverages a more performant algorithm such as dancing links (dlx). | ||
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| ## Usage | ||
| ```go | ||
| sudoku := sudoku.New(sudoku.EASY) // also available: MEDIUM, HARD, EXPERT | ||
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| fmt.Println(sudoku.Puzzle) // unsolved sudoku [81]int | ||
| fmt.Println(sudoku.Answer) // solved sudoku [81]int | ||
| ``` |
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| package sudoku | ||
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| import ( | ||
| "math/rand" | ||
| "time" | ||
| ) | ||
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| const ( | ||
| // available sudoku difficulties | ||
| EASY = 42 | ||
| MEDIUM = 36 | ||
| HARD = 27 | ||
| EXPERT = 25 | ||
| // time constraints | ||
| MAX_ATTEMPTS = 5 | ||
| MAX_EXEC_TIME = 3 | ||
| // sudoku board size | ||
| SUDOKU_LENGTH = 9 | ||
| SUDOKU_SIZE = SUDOKU_LENGTH * SUDOKU_LENGTH | ||
| ) | ||
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| type Sudoku struct { | ||
| Puzzle [SUDOKU_SIZE]int | ||
| Answer [SUDOKU_SIZE]int | ||
| } | ||
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| func New(difficulty int) *Sudoku { | ||
| for i := 0; i < MAX_ATTEMPTS; i++ { | ||
| if s, ok := newWithTimer(difficulty); ok { | ||
| return s | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
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| func newWithTimer(difficulty int) (*Sudoku, bool) { | ||
| s := &Sudoku{} | ||
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| done := make(chan struct{}) | ||
| var ok bool | ||
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| go func() { | ||
| s = &Sudoku{} | ||
| fill(&s.Puzzle) | ||
| s.Answer = s.Puzzle | ||
| s.eraseSome(difficulty) | ||
| close(done) | ||
| }() | ||
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| select { | ||
| case <-done: | ||
| ok = true | ||
| case <-time.After(time.Second * MAX_EXEC_TIME): | ||
| } | ||
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| return s, ok | ||
| } | ||
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| func (s *Sudoku) eraseSome(difficulty int) { | ||
| for erased := 0; SUDOKU_SIZE-erased > difficulty; { | ||
| idx := 0 | ||
| for s.Puzzle[idx] == 0 { | ||
| rand.Seed(time.Now().UnixNano()) | ||
| idx = rand.Intn(SUDOKU_SIZE) | ||
| } | ||
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| copyGrid := s.Puzzle | ||
| copyGrid[idx] = 0 | ||
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| count := 0 | ||
| solve(©Grid, &count) | ||
| if count == 1 { | ||
| s.Puzzle[idx] = 0 | ||
| erased++ | ||
| } | ||
| } | ||
| } | ||
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| func solve(grid *[SUDOKU_SIZE]int, count *int) { | ||
| if *count > 1 { // no need to go further | ||
| return | ||
| } | ||
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| for idx := 0; idx < SUDOKU_SIZE; idx++ { | ||
| if grid[idx] == 0 { | ||
| for n := 1; n <= SUDOKU_LENGTH; n++ { | ||
| if isValid(grid, idx, n) { | ||
| grid[idx] = n | ||
| if checkFull(grid) { | ||
| *count++ | ||
| } | ||
| solve(grid, count) | ||
| grid[idx] = 0 | ||
| } | ||
| } | ||
| break | ||
| } | ||
| } | ||
| } | ||
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| func fill(grid *[SUDOKU_SIZE]int) bool { | ||
| numberList := [SUDOKU_LENGTH]int{1, 2, 3, 4, 5, 6, 7, 8, 9} | ||
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| for idx := 0; idx < SUDOKU_SIZE; idx++ { | ||
| if grid[idx] == 0 { | ||
| rand.Seed(time.Now().UnixNano()) | ||
| rand.Shuffle(len(numberList), func(i, j int) { | ||
| numberList[i], numberList[j] = numberList[j], numberList[i] | ||
| }) | ||
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| for _, n := range numberList { | ||
| if isValid(grid, idx, n) { | ||
| grid[idx] = n | ||
| if checkFull(grid) || fill(grid) { | ||
| return true | ||
| } | ||
| grid[idx] = 0 | ||
| } | ||
| } | ||
| break | ||
| } | ||
| } | ||
| return false | ||
| } | ||
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| func checkFull(grid *[SUDOKU_SIZE]int) bool { | ||
| for i := 0; i < SUDOKU_SIZE; i++ { | ||
| if grid[i] == 0 { | ||
| return false | ||
| } | ||
| } | ||
| return true | ||
| } | ||
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| func isValid(grid *[SUDOKU_SIZE]int, idx, n int) bool { | ||
| // check if num is valid in row, col, and 3x3 box | ||
| row := idx / SUDOKU_LENGTH | ||
| col := idx % SUDOKU_LENGTH | ||
| for i := 0; i < SUDOKU_LENGTH; i++ { | ||
| if grid[row*SUDOKU_LENGTH+i] == n || | ||
| grid[i*SUDOKU_LENGTH+col] == n || | ||
| grid[((row/3)*3+i/3)*SUDOKU_LENGTH+((col/3)*3+i%3)] == n { | ||
| return false | ||
| } | ||
| } | ||
| return true | ||
| } |
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,45 @@ | ||
| package sudoku | ||
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| import ( | ||
| "fmt" | ||
| "testing" | ||
| ) | ||
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| func TestSudoku(t *testing.T) { | ||
| t.Log("TestSudoku") | ||
| var sudoku Sudoku | ||
| modes := map[int]string{ | ||
| EASY: "easy", | ||
| MEDIUM: "medium", | ||
| HARD: "hard", | ||
| EXPERT: "expert", | ||
| } | ||
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| for d, mode := range modes { | ||
| t.Log("Mode:", mode) | ||
| sudoku = *New(d) | ||
| t.Log(printSudoku(&sudoku)) | ||
| } | ||
| } | ||
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| func printSudoku(s *Sudoku) string { | ||
| board := "\n" | ||
| for i := 0; i < 81; i = i + 9 { | ||
| board += fmt.Sprintf("%d\n", s.Puzzle[i:i+9]) | ||
| } | ||
| board += "\n" | ||
| for i := 0; i < 81; i = i + 9 { | ||
| board += fmt.Sprintf("%d\n", s.Answer[i:i+9]) | ||
| } | ||
| notErased := 0 | ||
| for i := 0; i < 81; i++ { | ||
| if s.Puzzle[i] == 0 { | ||
| board += "." | ||
| } else { | ||
| board += fmt.Sprintf("%d", s.Puzzle[i]) | ||
| notErased++ | ||
| } | ||
| } | ||
| board += fmt.Sprintf("\nNot erased: %d", notErased) | ||
| return board | ||
| } |
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