Making a quadtree from a Matrix using recursion

[Anshul Singhal]

Hello guys,

I making a quadtree from a matrix. Please find attached with this post a sample image of how it is done. I ve used recursion but not able to get to the final result.

public quadtree make_quadtree(int a, int b, int c, int d)
   {
	//a,b are starting indexes of the matix and c,d are the ending ones.
      //link_matrix[m][n] is the actual matrix where the data is stored. It is of the type Link defined in a separate class.
       quadtree temp1 = new quadtree();
        quadtree temp2 = new quadtree();
        quadtree temp3 = new quadtree();
        quadtree temp4 = new quadtree();

    if((c-a)==1)
          {
			if((link_matrix[a+1][b].idata) != (link_matrix[a][b].idata))
				{
				        make_subtree(a,b);
                                }
                        else    
                                {
                                    if((link_matrix[a][b+1].idata) != (link_matrix[a+1][b+1].idata))
					{
	                                        make_subtree(a,b);
                                        }
                                     else 
                                        {
                                          	if((link_matrix[a][b].idata) != (link_matrix[a+1][b+1].idata))
						    {
 							make_subtree(a,b);
						    }
                        		 	 else 
                                            	   {
                                              	        this.make_one_node(a,b);
							
					            }   
                                         }
                                 }
            }
          else
	  {
         	 temp1 = make_quadtree(a,b,c/2,d/2);
                        temp2 = make_quadtree((c/2)+1,b,c,d/2);
                      temp3 = make_quadtree((c/2)+1,(d/2)+1,c,d);
		   	 temp4 = make_quadtree(a,(d/2)+1,c/2,d);
    		    	 Link newLink = new Link(-1, (temp1.first), (temp2.first), (temp3.first), (temp4.first));
       		 first = newLink;
          }
        return this;
   }

public void make_one_node(int a,int b)
   {
	Link newlink = new Link(link_matrix[a][b].idata,null,null,null,null);
        first = newlink;
     }

public void make_subtree(int a,int b)
   {
           Link newlink = new Link(-1,link_matrix[a][b],link_matrix[a+1][b],link_matrix[a+1][b+1],link_matrix[a][b+1]);
	   first = newlink;          
   }