func processSquare(i int, working working) working {
square := working[i]
square.checkValues(grid.IndicesForRow(i), working)
square.checkValues(grid.IndicesForColumn(i), working)
square.checkValues(grid.IndicesForSub(i), working)
if working[i].Value != square.Value {
working[i] = square
for _, index := range grid.IndicesForRow(i) {
if working[index].Value == 0 {
working = processSquare(index, working)
}
}
for _, index := range grid.IndicesForColumn(i) {
if working[index].Value == 0 {
working = processSquare(index, working)
}
}
for _, index := range grid.IndicesForSub(i) {
if working[index].Value == 0 {
working = processSquare(index, working)
}
}
}
return working
}
func (b multiBacktrackingSolver) Solve(given Grid) ([]Grid, error) {
var puzzle [81]backtrackSquare
for i, value := range given {
puzzle[i] = backtrackSquare{value: value, initial: value != 0}
}
var solutions []Grid
forward := true
i := 0
for {
if puzzle[i].initial {
if forward {
i++
} else {
i--
}
} else {
forward = true
puzzle[i].value++
ok := false
if puzzle[i].value > 9 {
puzzle[i].value = 0
forward = false
i--
} else {
ok = checkValues(grid.IndicesForColumn(i), puzzle[i].value, puzzle)
if ok {
ok = checkValues(grid.IndicesForRow(i), puzzle[i].value, puzzle)
}
if ok {
ok = checkValues(grid.IndicesForSub(i), puzzle[i].value, puzzle)
}
}
if ok {
i++
}
}
if i >= 81 {
// Puzzle is done record this solution and go back and find more
var ended [81]int
for i, square := range puzzle {
ended[i] = square.value
}
solutions = append(solutions, ended)
forward = false
i--
}
if i <= 0 {
// Found all the solutions
break
}
}
return solutions, nil
}
func (b randBacktrackingSolver) Solve(given Grid) (Grid, error) {
var puzzle [81]randBacktrackSquare
for i, value := range given {
puzzle[i] = randBacktrackSquare{
value: value,
initial: value != 0,
candidates: mixedValues(),
candidateIndex: -1}
}
forward := true
for i := 0; i < 81; {
if puzzle[i].initial {
if forward {
i++
} else {
i--
}
} else {
forward = true
ok := false
puzzle[i].candidateIndex++
if puzzle[i].outOfCandidates() {
puzzle[i].candidateIndex = -1
puzzle[i].value = 0
forward = false
i--
} else {
puzzle[i].value = puzzle[i].nextCandidate()
ok = randCheckValues(grid.IndicesForColumn(i), puzzle[i].value, puzzle)
if ok {
ok = randCheckValues(grid.IndicesForRow(i), puzzle[i].value, puzzle)
}
if ok {
ok = randCheckValues(grid.IndicesForSub(i), puzzle[i].value, puzzle)
}
}
if ok {
i++
}
}
}
var ended Grid
for i, square := range puzzle {
ended[i] = square.value
}
return ended, nil
}
func (b backtrackingSolver) Solve(given Grid) (Grid, error) {
var puzzle [81]backtrackSquare
for i, value := range given {
puzzle[i] = backtrackSquare{value: value, initial: value != 0}
}
forward := true
for i := 0; i < 81; {
if puzzle[i].initial {
if forward {
i++
} else {
i--
}
} else {
forward = true
puzzle[i].value++
ok := false
if puzzle[i].value > 9 {
puzzle[i].value = 0
forward = false
i--
} else {
ok = checkValues(grid.IndicesForColumn(i), puzzle[i].value, puzzle)
if ok {
ok = checkValues(grid.IndicesForRow(i), puzzle[i].value, puzzle)
}
if ok {
ok = checkValues(grid.IndicesForSub(i), puzzle[i].value, puzzle)
}
}
if ok {
i++
}
}
if i < 0 {
return Grid{}, errors.New("Unsolvable puzzle")
}
}
var ended [81]int
for i, square := range puzzle {
ended[i] = square.value
}
return ended, nil
}