public HashSet<Cell> jointCell(Cell aimCell) {
        HashSet<Cell> tempCells;
        tempCells = new HashSet<>();
        for (Cell tempCell : cells) {
            if (tempCell.openValues.size() == 1) continue;
            if (aimCell.x == tempCell.x) {
                tempCells.add(tempCell);
            }
            if (aimCell.y == tempCell.y) {
                tempCells.add(tempCell);
            }

            if ((tempCell.x > ((aimCell.x - 1) / 3) * 3) && (tempCell.x <= ((aimCell.x - 1) / 3) * 3 + 3) &&
                    (tempCell.y > ((aimCell.y - 1) / 3) * 3) && (tempCell.y <= ((aimCell.y - 1) / 3) * 3 + 3)) {
                tempCells.add(tempCell);
            }
        }
        tempCells.remove(aimCell);
        return tempCells;
    }