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/*
* $Revision: 2559 $
*
* last checkin:
* $Author: gutwenger $
* $Date: 2012-07-06 15:04:28 +0200 (Fr, 06. Jul 2012) $
***************************************************************/
/** \file
* \brief Declaration of class PQueue (priority queue).
*
* \author Stefan Hachul
*
* \par License:
* This file is part of the Open Graph Drawing Framework (OGDF).
*
* \par
* Copyright (C)<br>
* See README.txt in the root directory of the OGDF installation for details.
*
* \par
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* Version 2 or 3 as published by the Free Software Foundation;
* see the file LICENSE.txt included in the packaging of this file
* for details.
*
* \par
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* \par
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
* \see http://www.gnu.org/copyleft/gpl.html
***************************************************************/
#ifdef _MSC_VER
#pragma once
#endif
#ifndef OGDF_PQUEUE_H
#define OGDF_PQUEUE_H
#include "../basic/List.h"
namespace ogdf {
//Needed for storing entries of the heap.
class HelpRecord
{
public:
HelpRecord() { } //constructor
~HelpRecord(){ } //destructor
void set_ListIterator(ListIterator<PackingRowInfo>& it) { iterator = it; }
void set_value (double v) { value = v; }
ListIterator<PackingRowInfo> get_ListIterator() const { return iterator; }
double get_value() const { return value; }
private:
double value;
ListIterator<PackingRowInfo> iterator;
};
class PQueue
{
//Helping data structure that is a priority queue (heap) and holds double values
//(as comparison values) and iterators of type ListIterator<PackingRowInfo>
//as contents. It is needed in class MAARPacking for the Best_Fit insert strategy.
public:
PQueue() { P.clear(); } //constructor
~PQueue(){ } //destructor
//Inserts content with value value into the priority queue and restores the heap.
void insert(double value, ListIterator<PackingRowInfo> iterator)
{
HelpRecord h;
h.set_value(value);
h.set_ListIterator(iterator);
P.pushBack(h);
//reheap bottom up
reheap_bottom_up(P.size()-1);
}
//Deletes the element with the minimum value from the queue and restores
//the heap.
void del_min()
{
if(P.size() < 1)
cout<<"Error PQueue:: del_min() ; Heap is empty"<<endl;
else
{
//last element becomes first element
P.popFront();
if(!P.empty())
{
P.pushFront(P.back());
P.popBack();
//reheap top down
reheap_top_down(0);
}
}
}
//Returns the content with the minimum value.
ListIterator<PackingRowInfo> find_min()
{
OGDF_ASSERT(P.size() >= 1);
//if(P.size() < 1)
// cout<<"Error PQueue:: find_min() ; Heap is empty"<<endl;
//else
return P.front().get_ListIterator();
}
private:
List<HelpRecord> P;//the priority queue;
//Restores the heap property in P starting from position i bottom up.
void reheap_bottom_up(int i)
{
int parent = (i-1)/2;
if((i != 0) && ((*P.get(parent)).get_value() > (*P.get(i)).get_value()))
{
exchange(i,parent);
reheap_bottom_up(parent);
}
}
//Restores the heap property in P starting from position i top down.
void reheap_top_down(int i)
{
int smallest = i;
int l = 2*i+1;
int r = 2*i+2;
if((l <= P.size()-1) && ((*P.get(l)).get_value() < (*P.get(i)).get_value()))
smallest = l;
else
smallest = i;
if((r <= P.size()-1) && ((*P.get(r)).get_value() < (*P.get(smallest)).get_value()))
smallest = r;
if(smallest != i)//exchange and recursion
{
exchange(i,smallest);
reheap_top_down(smallest);
}
}
//Exchanges heap entries at positions i and j.
void exchange(int i, int j)
{
HelpRecord h = *P.get(i);
*P.get(i) = *P.get(j);
*P.get(j) = h;
}
};
}//namespace ogdf
#endif
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