disjsets.java

ALGAE是一个快速创建算法演示的框架。目前支持的算法实现语言包括java和c

/*{*/ // /*}*/package DataStructures;

/*{*/ import edu.odu.cs.zeil.AlgAE.Server.algae;
/*{*/ import edu.odu.cs.zeil.AlgAE.Server.Rendering;
/*{*/ import edu.odu.cs.zeil.AlgAE.Server.Visible;
/*{*/ import edu.odu.cs.zeil.AlgAE.Server.VisibleRendering;
/*{*/ import java.awt.Color;

// DisjSets class
//
// CONSTRUCTION: with int representing initial number of sets
//
// ******************PUBLIC OPERATIONS*********************
// void union( root1, root2 ) --> Merge two sets
// int find( x )              --> Return set containing x
// ******************ERRORS********************************
// No error checking is performed

/**
 * Disjoint set class, using union by rank
 * and path compression.
 * Elements in the set are numbered starting at 0.
 * @author Mark Allen Weiss
 */
public class DisjSets implements Visible
{
/*{*/     private VisibleRendering vr;
/*{*/ 
/*{*/     class DJSElement implements Visible
/*{*/     {
/*{*/         private VisibleRendering vr;
/*{*/         private int position;
/*{*/         
/*{*/         DJSElement (int i)
/*{*/         {
/*{*/             position = i;
/*{*/             vr = new VisibleRendering (this, java.awt.Color.cyan, false);
/*{*/         }
/*{*/ 
/*{*/         public Rendering getRendering() {return vr;}
/*{*/ 
/*{*/         public String getAlgAEText()
/*{*/         {
/*{*/             return "" + array[position];
/*{*/         }
/*{*/     
/*{*/         public void touchAllPointers() {}
/*{*/         
/*{*/         public void touchAllComponents() {}
/*{*/     }
/*{*/ 
/*{*/     private DJSElement[] visElements;
    
        
    /**
     * Construct the disjoint sets object.
     * @param numElements the initial number of disjoint sets.
     */
    public DisjSets( int numElements )
    {
        array = new int [ numElements ];
/*{*/         visElements = new DJSElement [numElements];
        for( int i = 0; i < array.length; i++ )
            {
                array[ i ] = -1;
/*{*/           visElements[i] = new DJSElement(i);
            }
/*{*/   vr = new VisibleRendering (this, java.awt.Color.blue, false);
    }

    /**
     * Union two disjoint sets using the height heuristic.
     * For simplicity, we assume root1 and root2 are distinct
     * and represent set names.
     * @param root1 the root of set 1.
     * @param root2 the root of set 2.
     */
    public void union( int root1, int root2 )
    {
/*{*/   algae.FRAME ("start a union");
        if( array[ root2 ] < array[ root1 ] )  /* root2 is deeper */
            {
/*{*/           algae.FRAME ("make root2 new root");
                array[ root1 ] = root2;        /* Make root2 new root */
            }
        else
	    {
/*{*/ 		algae.FRAME ("make root1 new root");
		if( array[ root1 ] == array[ root2 ] )
		    array[ root1 ]--;        /* Update height if same */
		array[ root2 ] = root1;        /* Make root1 new root */
	    }
/*{*/   algae.FRAME ("done with union");
    }

    /**
     * Perform a find with path compression.
     * Error checks omitted again for simplicity.
     * @param x the element being searched for.
     * @return the set containing x.
     */
    public int find( int x )
    {
/*{*/   algae.FRAME ("start to find");
        if( array[ x ] < 0 )
            {
/*{*/           algae.FRAME ("found the root");
                return x;
            }
        else
            {
/*{*/           algae.FRAME ("recurse to find");
                array[ x ] = find( array[ x ] );
/*{*/           algae.FRAME ("return from recursive find");
                return array[ x ];
            }
    }

    private int [ ] array;


    // Test main; all finds on same output line should be identical
    public static void main( String [ ] args )
    {
        int NumElements = 128;
        int NumInSameSet = 16;

        DisjSets s = new DisjSets( NumElements );
        int set1, set2;

        for( int k = 1; k < NumInSameSet; k *= 2 )
        {
            for( int j = 0; j + k < NumElements; j += 2 * k )
            {
                set1 = s.find( j );
                set2 = s.find( j + k );
                s.union( set1, set2 );
            }
        }

        for( int i = 0; i < NumElements; i++ )
        {
            System.out.print( s.find( i )+ "*" );
            if( i % NumInSameSet == NumInSameSet - 1 )
                System.out.println( );
        }
        System.out.println( );
    }


    
    public Rendering getRendering() {return vr;}

    public String getAlgAEText()
    {
        return "";
    }
    
    public void touchAllPointers() {}
    
    public void touchAllComponents()
    {
        for (int i = 0; i < visElements.length; i++ )
            vr.touch (visElements[i]);
    }
    
}