421 lines
10 KiB
C++
421 lines
10 KiB
C++
/*
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*
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* @APPLE_LICENSE_HEADER_START@
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*
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* Copyright (c) 1999-2008 Apple Inc. All Rights Reserved.
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*
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* This file contains Original Code and/or Modifications of Original Code
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* as defined in and that are subject to the Apple Public Source License
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* Version 2.0 (the 'License'). You may not use this file except in
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* compliance with the License. Please obtain a copy of the License at
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* http://www.opensource.apple.com/apsl/ and read it before using this
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* file.
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*
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* The Original Code and all software distributed under the License are
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* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
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* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
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* Please see the License for the specific language governing rights and
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* limitations under the License.
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*
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* @APPLE_LICENSE_HEADER_END@
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*
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*/
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/*
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File: OSHeap.cpp
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Contains: Implements a heap
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*/
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#include <string.h>
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#include "OSHeap.h"
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#include "OSMemory.h"
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OSHeap::OSHeap(UInt32 inStartSize)
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: fFreeIndex(1)
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{
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if (inStartSize < 2)
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fArraySize = 2;
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else
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fArraySize = inStartSize;
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fHeap = NEW OSHeapElem*[fArraySize];
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}
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void OSHeap::Insert(OSHeapElem* inElem)
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{
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Assert(inElem != NULL);
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if ((fHeap == NULL) || (fFreeIndex == fArraySize))
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{
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fArraySize *= 2;
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OSHeapElem** tempArray = NEW OSHeapElem*[fArraySize];
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if ((fHeap != NULL) && (fFreeIndex > 1))
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memcpy(tempArray, fHeap, sizeof(OSHeapElem*) * fFreeIndex);
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delete [] fHeap;
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fHeap = tempArray;
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}
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Assert(fHeap != NULL);
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Assert(inElem->fCurrentHeap == NULL);
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Assert(fArraySize > fFreeIndex);
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#if _OSHEAP_TESTING_
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SanityCheck(1);
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#endif
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//insert the element into the last leaf of the tree
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fHeap[fFreeIndex] = inElem;
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//bubble the new element up to its proper place in the heap
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//start at the last leaf of the tree
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UInt32 swapPos = fFreeIndex;
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while (swapPos > 1)
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{
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//move up the chain until we get to the root, bubbling this new element
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//to its proper place in the tree
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UInt32 nextSwapPos = swapPos >> 1;
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//if this child is greater than it's parent, we need to do the old
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//switcheroo
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if (fHeap[swapPos]->fValue < fHeap[nextSwapPos]->fValue)
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{
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OSHeapElem* temp = fHeap[swapPos];
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fHeap[swapPos] = fHeap[nextSwapPos];
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fHeap[nextSwapPos] = temp;
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swapPos = nextSwapPos;
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}
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else
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//if not, we are done!
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break;
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}
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inElem->fCurrentHeap = this;
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fFreeIndex++;
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}
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OSHeapElem* OSHeap::Extract(UInt32 inIndex)
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{
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if ((fHeap == NULL) || (fFreeIndex <= inIndex))
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return NULL;
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#if _OSHEAP_TESTING_
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SanityCheck(1);
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#endif
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//store a reference to the element we want to extract
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OSHeapElem* victim = fHeap[inIndex];
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Assert(victim->fCurrentHeap == this);
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victim->fCurrentHeap = NULL;
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//but now we need to preserve this heuristic. We do this by taking
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//the last leaf, putting it at the empty position, then heapifying that chain
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fHeap[inIndex] = fHeap[fFreeIndex - 1];
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fFreeIndex--;
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//The following is an implementation of the Heapify algorithm (CLR 7.1 pp 143)
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//The gist is that this new item at the top of the heap needs to be bubbled down
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//until it is bigger than its two children, therefore maintaining the heap property.
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UInt32 parent = inIndex;
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while (parent < fFreeIndex)
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{
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//which is bigger? parent or left child?
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UInt32 greatest = parent;
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UInt32 leftChild = parent * 2;
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if ((leftChild < fFreeIndex) && (fHeap[leftChild]->fValue < fHeap[parent]->fValue))
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greatest = leftChild;
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//which is bigger? the biggest so far or the right child?
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UInt32 rightChild = (parent * 2) + 1;
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if ((rightChild < fFreeIndex) && (fHeap[rightChild]->fValue < fHeap[greatest]->fValue))
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greatest = rightChild;
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//if the parent is in fact bigger than its two children, we have bubbled
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//this element down far enough
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if (greatest == parent)
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break;
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//parent is not bigger than at least one of its two children, so swap the parent
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//with the largest item.
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OSHeapElem* temp = fHeap[parent];
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fHeap[parent] = fHeap[greatest];
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fHeap[greatest] = temp;
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//now heapify the remaining chain
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parent = greatest;
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}
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return victim;
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}
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OSHeapElem* OSHeap::Remove(OSHeapElem* elem)
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{
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if ((fHeap == NULL) || (fFreeIndex == 1))
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return NULL;
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#if _OSHEAP_TESTING_
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SanityCheck(1);
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#endif
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//first attempt to locate this element in the heap
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UInt32 theIndex = 1;
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for ( ; theIndex < fFreeIndex; theIndex++)
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if (elem == fHeap[theIndex])
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break;
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//either we've found it, or this is a bogus element
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if (theIndex == fFreeIndex)
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return NULL;
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return Extract(theIndex);
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}
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#if _OSHEAP_TESTING_
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void OSHeap::SanityCheck(UInt32 root)
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{
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//make sure root is greater than both its children. Do so recursively
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if (root < fFreeIndex)
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{
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if ((root * 2) < fFreeIndex)
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{
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Assert(fHeap[root]->fValue <= fHeap[root * 2]->fValue);
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SanityCheck(root * 2);
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}
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if (((root * 2) + 1) < fFreeIndex)
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{
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Assert(fHeap[root]->fValue <= fHeap[(root * 2) + 1]->fValue);
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SanityCheck((root * 2) + 1);
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}
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}
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}
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Bool16 OSHeap::Test()
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{
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OSHeap victim(2);
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OSHeapElem elem1;
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OSHeapElem elem2;
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OSHeapElem elem3;
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OSHeapElem elem4;
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OSHeapElem elem5;
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OSHeapElem elem6;
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OSHeapElem elem7;
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OSHeapElem elem8;
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OSHeapElem elem9;
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OSHeapElem* max = victim.ExtractMin();
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if (max != NULL)
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return false;
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elem1.SetValue(100);
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victim.Insert(&elem1);
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max = victim.ExtractMin();
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if (max != &elem1)
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return false;
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max = victim.ExtractMin();
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if (max != NULL)
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return false;
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elem1.SetValue(100);
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elem2.SetValue(80);
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victim.Insert(&elem1);
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victim.Insert(&elem2);
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max = victim.ExtractMin();
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if (max != &elem2)
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return false;
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max = victim.ExtractMin();
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if (max != &elem1)
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return false;
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max = victim.ExtractMin();
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if (max != NULL)
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return false;
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victim.Insert(&elem2);
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victim.Insert(&elem1);
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max = victim.ExtractMin();
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if (max != &elem2)
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return false;
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max = victim.ExtractMin();
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if (max != &elem1)
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return false;
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elem3.SetValue(70);
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elem4.SetValue(60);
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victim.Insert(&elem3);
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victim.Insert(&elem1);
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victim.Insert(&elem2);
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victim.Insert(&elem4);
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max = victim.ExtractMin();
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if (max != &elem4)
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return false;
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max = victim.ExtractMin();
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if (max != &elem3)
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return false;
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max = victim.ExtractMin();
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if (max != &elem2)
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return false;
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max = victim.ExtractMin();
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if (max != &elem1)
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return false;
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elem5.SetValue(50);
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elem6.SetValue(40);
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elem7.SetValue(30);
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elem8.SetValue(20);
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elem9.SetValue(10);
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victim.Insert(&elem5);
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victim.Insert(&elem3);
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victim.Insert(&elem1);
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max = victim.ExtractMin();
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if (max != &elem5)
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return false;
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victim.Insert(&elem4);
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victim.Insert(&elem2);
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max = victim.ExtractMin();
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if (max != &elem4)
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return false;
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max = victim.ExtractMin();
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if (max != &elem3)
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return false;
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victim.Insert(&elem2);
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max = victim.ExtractMin();
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if (max != &elem2)
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return false;
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victim.Insert(&elem2);
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victim.Insert(&elem6);
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max = victim.ExtractMin();
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if (max != &elem6)
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return false;
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victim.Insert(&elem6);
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victim.Insert(&elem3);
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victim.Insert(&elem4);
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victim.Insert(&elem5);
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max = victim.ExtractMin();
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if (max != &elem6)
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return false;
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max = victim.ExtractMin();
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if (max != &elem5)
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return false;
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victim.Insert(&elem8);
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max = victim.ExtractMin();
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if (max != &elem8)
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return false;
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max = victim.ExtractMin();
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if (max != &elem4)
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return false;
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victim.Insert(&elem5);
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victim.Insert(&elem4);
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victim.Insert(&elem9);
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victim.Insert(&elem7);
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victim.Insert(&elem8);
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victim.Insert(&elem6);
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max = victim.ExtractMin();
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if (max != &elem9)
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return false;
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max = victim.ExtractMin();
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if (max != &elem8)
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return false;
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max = victim.ExtractMin();
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if (max != &elem7)
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return false;
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max = victim.ExtractMin();
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if (max != &elem6)
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return false;
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max = victim.ExtractMin();
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if (max != &elem5)
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return false;
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max = victim.ExtractMin();
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if (max != &elem4)
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return false;
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max = victim.ExtractMin();
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if (max != &elem3)
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return false;
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max = victim.ExtractMin();
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if (max != &elem2)
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return false;
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max = victim.ExtractMin();
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if (max != &elem2)
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return false;
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max = victim.ExtractMin();
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if (max != &elem1)
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return false;
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max = victim.ExtractMin();
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if (max != NULL)
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return false;
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victim.Insert(&elem1);
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victim.Insert(&elem2);
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victim.Insert(&elem3);
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victim.Insert(&elem4);
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victim.Insert(&elem5);
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victim.Insert(&elem6);
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victim.Insert(&elem7);
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victim.Insert(&elem8);
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victim.Insert(&elem9);
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max = victim.Remove(&elem7);
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if (max != &elem7)
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return false;
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max = victim.Remove(&elem9);
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if (max != &elem9)
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return false;
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max = victim.ExtractMin();
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if (max != &elem8)
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return false;
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max = victim.Remove(&elem2);
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if (max != &elem2)
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return false;
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max = victim.Remove(&elem2);
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if (max != NULL)
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return false;
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max = victim.Remove(&elem8);
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if (max != NULL)
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return false;
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max = victim.Remove(&elem5);
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if (max != &elem5)
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return false;
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max = victim.Remove(&elem6);
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if (max != &elem6)
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return false;
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max = victim.Remove(&elem1);
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if (max != &elem1)
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return false;
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max = victim.ExtractMin();
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if (max != &elem4)
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return false;
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max = victim.Remove(&elem1);
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if (max != NULL)
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return false;
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return true;
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}
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#endif
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