private Grid solve(Grid grid) {
if (grid.getRemainingSquares() == 0 && grid.getRemainingCandidates() == 0) {
return grid;
}
Set<Move> moves = grid.findCandidateMoves();
if (moves.isEmpty()) {
return null;
}
Move bestMove = moves.iterator().next();
if (bestMove.remainingSquares == 0 && bestMove.remainingCandidates == 0) {
grid.printCandidates();
System.out.println("\n" + bestMove + "\n");
bestMove.executeMove(grid);
return grid;
}
for (Move move : moves) {
System.out.println("\n" + move + "\n");
Grid clone = new Grid(grid);
move.executeMove(clone);
Grid result = clone.solve();
if (result != null) {
return result;
}
}
return null;
}
public static Set<Move> findLegalMoves(Grid grid, int depth) {
if (grid.getRemainingSquares() == 0 || depth == 0) {
return null;
} else {
Set<Move> candidateMoves = grid.findCandidateMoves();
Set<Move> legalMoves = new LinkedHashSet<Move>(candidateMoves);
for (Move move : candidateMoves) {
Grid clone = new Grid(grid);
move.executeMove(clone);
Set<Move> nextMoves = findLegalMoves(grid, depth - 1);
if (nextMoves != null && nextMoves.isEmpty()) {
legalMoves.remove(candidateMoves);
}
}
return candidateMoves;
}
}
public void executeMove(Grid grid) {
grid.setValue(this.row, this.col, this.value);
remainingSquares = grid.getRemainingSquares();
remainingCandidates = grid.getRemainingCandidates();
}