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/*
* $Revision: 2524 $
*
* last checkin:
* $Author: gutwenger $
* $Date: 2012-07-03 09:54:22 +0200 (Tue, 03 Jul 2012) $
***************************************************************/
/** \file
* \brief Declaration of a base class for planar representations
* of graphs and cluster graphs.
*
* \author Hoi-Ming Wong
*
* \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_MIN_PRIORITY_QUEUE_H
#define OGDF_MIN_PRIORITY_QUEUE_H
#include<ogdf/basic/Array.h>
namespace ogdf {
template<class Score, class X>
class HeapElement {
template<class T1, class T2> friend class MinPriorityQueue;
private:
Score v;
X x;
int pos; // the position in the heapElement array
public:
HeapElement(){}
//copy constructor
HeapElement(const HeapElement<Score, X> &orig): v(orig.v), x(orig.x), pos(orig.pos) {}
HeapElement(Score vt, X xt) : v(vt), x(xt) {}
//return the score
Score score_value() const { return v; }
// return the element
X element() const { return x;}
};
// using min heaps
// follow the pseudo code of "introduction to algorithms"
template <class Score, class X>
class MinPriorityQueue {
private :
HeapElement<Score, X> **heapElements;
int number; // the number of elements in the Queue
int s; // size
void swap(int pos1, int pos2) {
HeapElement<Score, X> *tmp = heapElements[pos1];
heapElements[pos1] = heapElements[pos2];
heapElements[pos2] = tmp;
// update the position
heapElements[pos2]->pos = pos2;
heapElements[pos1]->pos = pos1;
}
void minHeapify(int pos) {
int l = getLeft(pos);
int r = getRight(pos);
int smallest;
if (l <= number && heapElements[l]->score_value() < heapElements[pos]->score_value() )
smallest = l;
else
smallest = pos;
if (r <= number && heapElements[r]->score_value() < heapElements[smallest]->score_value())
smallest = r;
if (smallest != pos) {
swap(pos, smallest);
minHeapify(smallest);
}
}
int getParent(int pos) const {return pos/2;}
int getLeft(int pos) const {return pos*2;}
int getRight(int pos) const {return pos*2+1;}
public:
// contructor, only fixed size
MinPriorityQueue(int _size) : number(0), s(_size) {
heapElements = new HeapElement<Score, X>* [_size+1]; // allocate
for (int i = 0; i < s+1; ++i) {
heapElements[i] = 0;
}
}
~MinPriorityQueue() {
for (int i = 0; i < s+1; ++i) {
if (heapElements[i] != 0) {
delete heapElements[i];
heapElements[i] = 0;
}
}
delete [] heapElements;
}
bool empty() const { return number == 0; }
int count() const { return number; }
int size() const { return s; }
//return the Object with the min. score
const X & getMin() const {
return heapElements[1]->element();
}
void decreasePriority(const HeapElement<Score, X> *elem, // handle to the element
Score sc // new score, muss be smaller then the old score
) {
int i = elem->pos;
OGDF_ASSERT(i <= s);
if (heapElements[i]->score_value() < sc)
throw "New key is greater than current key.";
heapElements[i]->v = sc;
while (i > 1 && (heapElements[getParent(i)]->score_value() > heapElements[i]->score_value()) ) {
swap(i, getParent(i));
i = getParent(i);
}
}
// return a handle to the new inserted element
const HeapElement<Score, X> * insert(const HeapElement<Score, X> &elem) {
HeapElement<Score, X> *h_elem = new HeapElement<Score, X>(elem); // make a copy
++number;
OGDF_ASSERT(number <= s);
h_elem->pos = number; // store the position
heapElements[number] = h_elem;
int i = number;
while ( (i > 1) && ( heapElements[getParent(i)]->score_value() > heapElements[i]->score_value()) ) {
swap(i, getParent(i));
i = getParent(i);
}
return h_elem;
}
// return the smallest element and remove it from the queue
HeapElement<Score, X> pop() {
if (empty())
throw "Heap underflow error!";
HeapElement<Score, X> obj = *heapElements[1];
HeapElement<Score, X> * p = heapElements[1];
swap(1, number);
--number;
delete p;
minHeapify(1);
OGDF_ASSERT(number+1 <= s);
heapElements[number+1] = 0;
return obj;
}
/*********************************************************************************/
// debug
void outHeap() {
cout << "\nHeap Array: \n";
for (int i = 0; i < s+1; i++) {
HeapElement<Score, X> *obj = heapElements[i];
if (obj != NULL)
cout << "score: " << obj->score_value() << "; elem: " << obj->element() << "; index "<< i << "; pos: " << obj->pos << endl << flush;
else
cout << "index: " << i << " value: null;" << endl << flush;
}
}
};
}// namespace
#endif
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