private static void solve(Grid grid, List<Grid> solutions) {
// Return if there is already more than two solution
if (solutions.size() >= 2) {
return;
}
// Find first empty cell
int loc = grid.findEmptyCell();
// If no empty cells are found,a solution is found
if (loc < 0) {
solutions.add(grid.clone());
return;
}
// Try each of the 9 digits in this empty cell
for (int n = 1; n < 10; n++) {
if (grid.set(loc, n)) {
// With this cell set,work on the next cell
solve(grid, solutions);
// Clear the cell so that it can be filled with another digit
grid.clear(loc);
}
}
}
private int guess() {
for (int i = s; i > 0; i--) {
for (int j = 0; j < s; j++) {
for (int k = 0; k < s; k++) {
if (!grid.cellFilled(j, k) && grid.possible(j, k, i)) {
grids.push(grid.clone());
guesses.push(new int[] {j, k, i});
// System.out.println("guessing row: "+j+" col: "+k+" is "+i );
// System.out.println(grids.size() + "");
int r = grid.setCellVal(j, k, i);
// System.out.println(grid);
if (r == 1) {
System.out.println("solved");
return 1;
} else if (r == -1) {
while (r == -1) {
if (grids.isEmpty()) {
System.out.println("unsolvable");
return -1;
}
int[] lastGuess = guesses.pop();
// System.out.println("bad guess, removing
// possibility of row: " + lastGuess[0] + " col: " + lastGuess[1] + " being " +
// lastGuess[2]);
// System.out.println(grid);
grid = grids.pop();
// System.out.println(grids.size() + "");
r = grid.setCellNot(lastGuess[0], lastGuess[1], lastGuess[2]);
}
return r;
} else {
System.out.println("not enough info");
return 0;
}
}
}
}
}
return -1;
}
public Solution<Integer> solve() {
final Grid<Integer> workingGrid = _initialGrid.clone();
Coord.overGrid(_width, _height)
.forEach(
from ->
from.surroundsWithDiagonals(_width, _height)
.forEach(to -> applyConstraint(from, to, workingGrid)));
workingGrid.traverse(new ConsolePrintingVisitor<>(System.out));
for (final Group group : _groupByCoord.values()) {
for (final Coord from : group.getCoords()) {
for (final Coord to : group.getCoords()) {
if (!from.equals(to)) {
applyConstraint(from, to, workingGrid);
}
}
}
}
workingGrid.traverse(new ConsolePrintingVisitor<>(System.out));
return new Solution<>(SolutionType.NONE, Optional.<Grid<Integer>>empty());
}