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257 lines
6.4 KiB
C
257 lines
6.4 KiB
C
/*
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* SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
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* Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice including the dates of first publication and
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* either this permission notice or a reference to
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* http://oss.sgi.com/projects/FreeB/
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* shall be included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* SILICON GRAPHICS, INC. BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
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* OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* Except as contained in this notice, the name of Silicon Graphics, Inc.
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* shall not be used in advertising or otherwise to promote the sale, use or
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* other dealings in this Software without prior written authorization from
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* Silicon Graphics, Inc.
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*/
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/*
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** Author: Eric Veach, July 1994.
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**
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*/
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#include <stddef.h>
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#include <assert.h>
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#include "priorityq-heap.h"
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#include "memalloc.h"
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#define INIT_SIZE 32
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#ifndef TRUE
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#define TRUE 1
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#endif
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#ifndef FALSE
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#define FALSE 0
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#endif
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#ifdef FOR_TRITE_TEST_PROGRAM
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#define LEQ(x,y) (*pq->leq)(x,y)
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#else
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/* Violates modularity, but a little faster */
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#include "geom.h"
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#define LEQ(x,y) VertLeq((GLUvertex *)x, (GLUvertex *)y)
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#endif
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/* really __gl_pqHeapNewPriorityQ */
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PriorityQ *pqNewPriorityQ( int (*leq)(PQkey key1, PQkey key2) )
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{
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PriorityQ *pq = (PriorityQ *)memAlloc( sizeof( PriorityQ ));
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if (pq == NULL) return NULL;
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pq->size = 0;
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pq->max = INIT_SIZE;
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pq->nodes = (PQnode *)memAlloc( (INIT_SIZE + 1) * sizeof(pq->nodes[0]) );
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if (pq->nodes == NULL) {
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memFree(pq);
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return NULL;
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}
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pq->handles = (PQhandleElem *)memAlloc( (INIT_SIZE + 1) * sizeof(pq->handles[0]) );
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if (pq->handles == NULL) {
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memFree(pq->nodes);
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memFree(pq);
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return NULL;
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}
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pq->initialized = FALSE;
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pq->freeList = 0;
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pq->leq = leq;
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pq->nodes[1].handle = 1; /* so that Minimum() returns NULL */
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pq->handles[1].key = NULL;
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return pq;
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}
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/* really __gl_pqHeapDeletePriorityQ */
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void pqDeletePriorityQ( PriorityQ *pq )
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{
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memFree( pq->handles );
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memFree( pq->nodes );
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memFree( pq );
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}
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static void FloatDown( PriorityQ *pq, long curr )
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{
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PQnode *n = pq->nodes;
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PQhandleElem *h = pq->handles;
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PQhandle hCurr, hChild;
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long child;
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hCurr = n[curr].handle;
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for( ;; ) {
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child = curr << 1;
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if( child < pq->size && LEQ( h[n[child+1].handle].key,
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h[n[child].handle].key )) {
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++child;
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}
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assert(child <= pq->max);
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hChild = n[child].handle;
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if( child > pq->size || LEQ( h[hCurr].key, h[hChild].key )) {
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n[curr].handle = hCurr;
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h[hCurr].node = curr;
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break;
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}
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n[curr].handle = hChild;
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h[hChild].node = curr;
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curr = child;
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}
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}
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static void FloatUp( PriorityQ *pq, long curr )
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{
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PQnode *n = pq->nodes;
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PQhandleElem *h = pq->handles;
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PQhandle hCurr, hParent;
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long parent;
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hCurr = n[curr].handle;
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for( ;; ) {
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parent = curr >> 1;
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hParent = n[parent].handle;
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if( parent == 0 || LEQ( h[hParent].key, h[hCurr].key )) {
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n[curr].handle = hCurr;
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h[hCurr].node = curr;
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break;
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}
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n[curr].handle = hParent;
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h[hParent].node = curr;
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curr = parent;
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}
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}
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/* really __gl_pqHeapInit */
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void pqInit( PriorityQ *pq )
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{
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long i;
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/* This method of building a heap is O(n), rather than O(n lg n). */
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for( i = pq->size; i >= 1; --i ) {
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FloatDown( pq, i );
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}
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pq->initialized = TRUE;
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}
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/* really __gl_pqHeapInsert */
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/* returns LONG_MAX iff out of memory */
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PQhandle pqInsert( PriorityQ *pq, PQkey keyNew )
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{
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long curr;
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PQhandle free_handle;
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curr = ++ pq->size;
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if( (curr*2) > pq->max ) {
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PQnode *saveNodes= pq->nodes;
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PQhandleElem *saveHandles= pq->handles;
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/* If the heap overflows, double its size. */
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pq->max <<= 1;
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pq->nodes = (PQnode *)memRealloc( pq->nodes,
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(size_t)
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((pq->max + 1) * sizeof( pq->nodes[0] )));
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if (pq->nodes == NULL) {
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pq->nodes = saveNodes; /* restore ptr to free upon return */
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return LONG_MAX;
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}
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pq->handles = (PQhandleElem *)memRealloc( pq->handles,
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(size_t)
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((pq->max + 1) *
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sizeof( pq->handles[0] )));
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if (pq->handles == NULL) {
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pq->handles = saveHandles; /* restore ptr to free upon return */
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return LONG_MAX;
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}
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}
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if( pq->freeList == 0 ) {
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free_handle = curr;
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} else {
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free_handle = pq->freeList;
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pq->freeList = pq->handles[free_handle].node;
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}
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pq->nodes[curr].handle = free_handle;
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pq->handles[free_handle].node = curr;
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pq->handles[free_handle].key = keyNew;
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if( pq->initialized ) {
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FloatUp( pq, curr );
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}
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assert(free_handle != LONG_MAX);
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return free_handle;
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}
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/* really __gl_pqHeapExtractMin */
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PQkey pqExtractMin( PriorityQ *pq )
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{
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PQnode *n = pq->nodes;
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PQhandleElem *h = pq->handles;
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PQhandle hMin = n[1].handle;
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PQkey min = h[hMin].key;
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if( pq->size > 0 ) {
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n[1].handle = n[pq->size].handle;
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h[n[1].handle].node = 1;
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h[hMin].key = NULL;
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h[hMin].node = pq->freeList;
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pq->freeList = hMin;
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if( -- pq->size > 0 ) {
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FloatDown( pq, 1 );
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}
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}
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return min;
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}
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/* really __gl_pqHeapDelete */
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void pqDelete( PriorityQ *pq, PQhandle hCurr )
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{
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PQnode *n = pq->nodes;
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PQhandleElem *h = pq->handles;
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long curr;
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assert( hCurr >= 1 && hCurr <= pq->max && h[hCurr].key != NULL );
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curr = h[hCurr].node;
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n[curr].handle = n[pq->size].handle;
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h[n[curr].handle].node = curr;
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if( curr <= -- pq->size ) {
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if( curr <= 1 || LEQ( h[n[curr>>1].handle].key, h[n[curr].handle].key )) {
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FloatDown( pq, curr );
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} else {
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FloatUp( pq, curr );
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}
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}
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h[hCurr].key = NULL;
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h[hCurr].node = pq->freeList;
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pq->freeList = hCurr;
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}
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