%-- 15.11.08 17:47 --%
function SudokuFree()
start

global reihenzellen
global spaltenzellen
global hauptzellen
global Zelle
 
    function start()

    %<--------Graphische Oberfläche----------->
    figure('name', 'Soduko löser', 'Color', [1 1 1], 'Units', 'pixels','Position', [300 300 378 458])
    spaceX = 0;
    spaceY = 0;    
    for i = 1:9  
        if i == 4 || i == 7   
            spaceY = spaceY + 10;
        end
        spaceX = 0;
        for a = 1:9
            if a == 4 || a == 7
                spaceX = spaceX + 10;
            end
                    uicontrol('Style','edit','position', [50+(a-1)*30+spaceX, 77+(i-1)*30+spaceY,21,21]);      
        end        
    end

    uicontrol('Style','push','String','Soduko lösen','position', [70 ,32 ,80, 26],'Callback',@pushbutton1_Callback);
    uicontrol('Style','push','String','Zurücksetzen','position', [220 ,32 ,80, 26],'Callback', @pushbutton2_Callback);
    uicontrol('Style','text','BackgroundColor', [1 1 1],'FontSize', 25,'String','Sodukolöser','position', [59, 380, 257, 51]);
    uicontrol('Style','text','BackgroundColor', [1 1 1],'String','von Isabelle Wetzstein','position', [250, 8, 113, 16]);
    %<--------Graphische Oberfläche----------->
    
    %<---------Variablen zum Lösen------------> 
      reihenzellen = cell(81,8);
      spaltenzellen = cell(81,8);
      hauptzellen = cell(81,8);

      for reihe = 1:9
        for spalte = 1:9                
          position = (reihe-1) * 9 + spalte;
          i = 1;
          for s = 1:9
            if (s ~= spalte)  
              reihenzellen{position,i} = (reihe-1) * 9 + (s-1)+1;
              i = i+1;
            end
          end
          i = 1;
          for r = 1:9
            if (r ~= reihe)  
              spaltenzellen{position,i} = 9 * (r-1) + spalte;
              i = i+1;
            end
          end
          hauptreihe = floor((reihe-1) / 3);
          hauptspalte = floor((spalte-1) / 3);
          i = 1;
          for hr = 0:2 
            for hs = 0:2
              index = (((hauptreihe * 3) + hr) * 9) + (hauptspalte * 3) + hs+1; 
              if (index ~= position)  
                hauptzellen{position,i} = index;
                i = i+1;
              end
            end
          end
        end
      end
    
    end

    function s = loese(position, Zelle) 
      s = false;
      if position > 81 
          h=findobj('style','edit'); 
          i = 0;
          for k=h'  
              i = i + 1;
              set(k,'string',Zelle(i))
          end
          disp ('Erfolgreich gelöst!');
          s = true;
          return;
      end

      if (Zelle(position) == 0)  
        for i = 1:9 
          if (teste(position, i, Zelle)) 
            Zelle(position) = i; 
            if (loese(position + 1, Zelle))
                s = true;
                return;
            else
                Zelle(position) = 0;
            end
         end
       end
       s = false;
       else
        loese(position + 1, Zelle);
        return;
      end
    end

    function y = teste(position, value, Zelle)   
          for i = 1:8
            if (Zelle(reihenzellen{position,i}) == value)  
                y = false;
                return;
            end
            if (Zelle(spaltenzellen{position,i}) == value)  
                y = false;
                return;
            end
            if (Zelle(hauptzellen{position,i}) == value)  
                y =  false;
                return;
            end
          end
         y = true;
end

    function pushbutton1_Callback(hObject, eventdata, handles)
        h=findobj('style','edit');
        i = 0;
        Fehler = 0;
        for k=h'  
           i = i + 1;
           z = str2num(get(k,'string'));
           if z < 10 
               Zelle(i) = z;
           else          
               Zelle(i) = 0;
           end
        end
        
        for position = 1:81
            if Zelle(position) ~= 0
                if (~teste(position, Zelle(position), Zelle)) 
                    msgbox('Das Sudoku konnte nicht gelöst werden, weil es Fehler enthält!!');
                    ausgabe = '';
                    Fehler = 1;
                    break; 
                end
            end
        end
        if Fehler ~= 1
            loese(1, Zelle)
        end
    end

    function pushbutton2_Callback(hObject, eventdata, handles)
        h=findobj('style','edit'); 
        for k=h'  
            set(k,'string','');  
        end
    end

end