Alunos unidos jamais... tomarao PAU!

[daniel.lacerda@poli.usp.br]

/* Extract the highest priority from the heap */

#define LEFT(k)         (2*k)
#define RIGHT(k)        (2*k+1)
#define EMPTY(c,k)      (k>=c->item_cnt)
#define SWAP(i,j)       { void *x = c->items[i]; \
                        c->items[i] = c->items[j]; \
                        c->items[j] = x; }

void MoveDown( Collection c, int k )
        {
        int larger, right, left;
        left = LEFT(k);
        right = RIGHT(k);
        if ( !EMPTY(c,k) )      /* Termination condition! */
                {
                larger=left;
                if ( !EMPTY(c,right) )
                        {
                        if ( ItemCmp( c->items[right], c->items[larger]
) > 0 )
                                larger = right;
                        }
                if ( ItemCmp( c->items[k], c->items[larger] ) )
                        {
                        SWAP( k, larger );
                        MoveDown( c, larger );
                        }
                }
        }

void *HighestPriority( Collection c )
/* Return the highest priority item
   Pre-condition: (c is a collection created by a call to
                     ConsCollection) &&
                  (existing item count >= 1) &&
                  (item != NULL)
   Post-condition: item has been deleted from c
*/
        {
        int i, cnt;
        void *save;
        assert( c != NULL );
        assert( c->item_cnt >= 1 );
        /* Save the root */
        save = c->items[0];
        /* Put the last item in the root */
        cnt = c->item_cnt;
        c->items[0] = c->items[cnt-1];
        /* Adjust the count */
        c->item_cnt--;
        /* Move the new root item down if necessary */
        MoveDown( c, 1 );
        return save;
        }


FONTE:
http://ciips.ee.uwa.edu.au/~morris/Year2/PLDS210/source/heap_delete.c



-- 
/*----------------------------------------------------------------        
  Daniel da Silva Lacerda
  Graduando em Engenharia Eletrica - daniel.lacerda@poli.usp.br
  Laboratorio de Tecnicas Inteligentes - www.lti.pcs.usp.br
  Escola Politecnica da USP - www.poli.usp.br
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