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/*
* Copyright (C) 2007-2013 Frank Mertens.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef DRY_HEAP_HPP
#define DRY_HEAP_HPP
#include "containers.hpp"
namespace dry
{
template<class T, template<class T> class Order = Ascending>
class GenericHeap: public Container< T, GenericHeap<T, Order> >, public Order<T>
{
public:
typedef T Item;
~GenericHeap()
{
if (bufOwner_)
{
delete[] buf_;
buf_ = 0;
}
}
inline int size() const { return size_; }
inline int fill() const { return fill_; }
inline int length() const { return fill_; }
inline bool isFull() const { return fill_ == size_; }
inline bool isEmpty() const { return fill_ == 0; }
inline void push(const T &item)
{
DRY_ASSERT(fill_ < size_);
buf_[fill_] = item;
++fill_;
passUpLast();
}
inline void pop(T *item)
{
DRY_ASSERT(fill_ > 0);
*item = buf_[0];
--fill_;
buf_[0] = buf_[fill_];
passDownFromTop();
}
inline T pop() {
T item;
pop(&item);
return item;
}
inline T top() { DRY_ASSERT(!isEmpty()); return buf_[0]; }
inline void clear() { fill_ = 0; }
inline static int parent(int i) { return (i - 1) / 2; }
inline static int leftChild(int i) { return 2 * i + 1; }
inline static int rightChild(int i) { return 2 * i + 2; }
void xchg(int i, int j)
{
T h = buf_[i];
buf_[i] = buf_[j];
buf_[j] = h;
}
int min(int i, int j, int k)
{
int h = Order<T>::below(buf_[i], buf_[j]) ? i : j;
return Order<T>::below(buf_[h], buf_[k]) ? h : k;
}
void passUpLast()
{
if (fill_ == 1) return;
int i = fill_ - 1;
while (i != 0) {
int j;
j = parent(i);
if (Order<T>::below(buf_[j], buf_[i])) break;
xchg(i, j);
i = j;
}
}
void passDownFromTop()
{
if (fill_ == 0) return;
int i = 0;
while (true) {
int j, lc, rc;
lc = leftChild(i);
rc = rightChild(i);
if (rc < fill_) {
j = min(i, lc, rc);
if (j == i) break;
xchg(i, j);
i = j;
}
else if (lc < fill_) {
if (Order<T>::below(buf_[lc], buf_[i])) xchg(i, lc);
break;
}
else
break;
}
}
protected:
GenericHeap(int size)
: fill_(0),
size_(size),
bufOwner_(true),
buf_(new T[size])
{}
GenericHeap(T *buf, int size)
: fill_(0),
size_(size),
bufOwner_(false),
buf_(buf)
{}
int fill_; // current number of elements
int size_; // maximal number of elements
bool bufOwner_;
T *buf_; // memory buffer used for storing elements
};
template<class T>
class Heap: public GenericHeap<T, FlexibleSortOrder>
{
public:
typedef GenericHeap<T, FlexibleSortOrder> Super;
inline static Ref<Heap> create(int size, int order = SortOrder::Ascending) {
return new Heap(size, order);
}
inline static Ref<Heap> create(T *buf, int size, int order = SortOrder::Ascending) {
return new Heap(buf, size, order);
}
void reset(int order) {
Super::clear();
Super::setSortOrder(order);
}
private:
Heap(int size, int order)
: GenericHeap<T, FlexibleSortOrder>(size)
{
Super::setSortOrder(order);
}
Heap(T *buf, int size, int order)
: GenericHeap<T, FlexibleSortOrder>(buf, size)
{
Super::setSortOrder(order);
}
};
template<class T>
class MinHeap: public GenericHeap<T, Ascending>
{
public:
inline static Ref<MinHeap> create(int size) {
return new MinHeap(size);
}
inline static Ref<MinHeap> create(T *buf, int size) {
return new MinHeap(buf, size);
}
private:
MinHeap(int size): GenericHeap<T, Ascending>(size) {}
MinHeap(T *buf, int size): GenericHeap<T, Ascending>(buf, size) {}
};
template<class T>
class MaxHeap: public GenericHeap<T, Descending>
{
public:
inline static Ref<MaxHeap> create(int size) {
return new MaxHeap(size);
}
inline static Ref<MaxHeap> create(T *buf, int size) {
return new MaxHeap(buf, size);
}
private:
MaxHeap(int size): GenericHeap<T, Descending>(size) {}
MaxHeap(T *buf, int size): GenericHeap<T, Descending>(buf, size) {}
};
} // namespace dry
#endif // DRY_HEAP_H
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