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src/bheap.c  view on Meta::CPAN

     * the item to be deleted.
     */
    n = --(h->n);
    p = h->p[item];

    /* Heap needs adjusting if the position of the deleted item was not at the
     * end of the heap.
     */
    if(p <= n) {
        /* We put the item at the end of the heap in the place of the deleted
         * item and sift-up or sift-down to relocate it in the correct place in
         * the heap.
         */
	h->key_comps++;
        if(h->a[p].key <= h->a[n + 1].key) {
            h->a[p] = h->a[n + 1];
            h->p[h->a[p].item] = p;
            bh_siftup(h, p, n);
        }
        else {
            /* Use insert to sift-down, temporarily adjusting the size of the

src/bheap.c  view on Meta::CPAN

             */
            h->n = p - 1;
            bh_insert(h, h->a[n + 1].item, h->a[n+1].key);
            h->n = n;
        }
    }
}


/* bh_decrease_key() decreases the value of 'item's key and then performs
 * sift-down until 'item' has been relocated to the correct position in the
 * binary heap.
 */
void bh_decrease_key(bheap_t *h, int item, long new_key)
{
    int n;

    n = h->n;
    h->n = h->p[item] - 1;

    bh_insert(h, item, new_key);

src/bheap.h  view on Meta::CPAN

/* bh_insert() inserts an item and its key value into the binary heap pointed
 * to by h.
 */
void bh_insert(bheap_t *h, int item, long key);

/* bh_delete() deletes an item from the binary heap pointed to by h.
 */
void bh_delete(bheap_t *h, int item);

/* bh_decrease_key() decreases the value of 'item's key and then performs
 * sift-down until 'item' has been relocated to the correct position in the
 * binary heap.
 */
void bh_decrease_key(bheap_t *h, int item, long new_key);

void bh_dump(bheap_t *h);

/*** Alternative interface via the universal heap structure type. ***/
extern const heap_info_t BHEAP_info;

#endif