/usr/lib/grass64/include/grass/iostream/pqheap.h is in grass-dev 6.4.3-3.
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*
* MODULE: iostream
*
* COPYRIGHT (C) 2007 Laura Toma
*
* 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.
*
* 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.
*
*****************************************************************************/
#ifndef _PQHEAP_H
#define _PQHEAP_H
#include <assert.h>
#include <stdlib.h>
#define PQHEAP_MEM_DEBUG if(0)
//HEAPSTATUS can be defined at compile time
//this flag is currently off; we used it at some point for checking
//how many times is each element in the heap accessed or something
//like that
#ifdef HEAPSTATUS
static const int PAGESIZE = 1024;
#endif
// Helper functions for navigating through a binary heap.
/* for simplicity the heap structure is slightly modified as:
0
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/\
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*/
// The children of an element of the heap.
static inline unsigned int heap_lchild(unsigned int index) {
return 2 * index;
}
static inline unsigned int heap_rchild(unsigned int index) {
return 2 * index + 1;
}
// The parent of an element.
static inline unsigned int heap_parent(unsigned int index) {
return index >> 1;
}
// return minimum of two integers
static unsigned int mymin(unsigned int a, unsigned int b) {
return (a<=b)? a:b;
}
/**************************************************************
***************************************************************
***************************************************************
Priority queue templated on a single type
assume T to be a class with getPriority() and getValue() implemented;
Supported operations: min, extract_min, insert in O(lg n)
***************************************************************
***************************************************************
***************************************************************/
template <class T>
class pqheap_t1 {
// A pointer to an array of elements
T* elements;
// The number of elements currently in the queue.
unsigned int cur_elts;
// The maximum number the queue can hold.
unsigned int max_elts;
private:
void heapify(unsigned int root);
public:
inline pqheap_t1(unsigned int size);
//build heap from an array of elements; array a is REUSED, and NOT
//COPIED, for efficiency; it'd better not be used after this
//outside!!!
inline pqheap_t1(T* a, unsigned int size);
inline ~pqheap_t1(void);
//build a heap from an array of elements;
//if size > max_elts, insert first maxsize elements from array;
//return nb of elements that did not fit;
unsigned int fill(T* a, unsigned int size);
// Is it full?
inline bool full(void);
//Is it empty?
inline bool empty(void);
inline bool is_empty() { return empty(); };
// How many elements?
inline unsigned int num_elts(void);
// How many elements? sorry - i could never remember num_elts
inline unsigned int size(void) const { return cur_elts; };
// Min
inline bool min(T& elt);
T min();
// Extract min and set elt = min
inline bool extract_min(T& elt);
//extract all elts with min key, add them and return their sum
inline bool extract_all_min(T& elt);
//delete min; same as extract_min, but ignore the value extracted
inline bool delete_min();
// Insert
inline bool insert(const T& elt);
//Delete the current minimum and insert the new item x;
//the minimum item is lost (i.e. not returned to user);
//needed to optimize merge
inline void delete_min_and_insert(const T &x);
//this function is a dirty way to allow building faster the heap
//in case we build it from a sorted array; in that case we dont need
//to 'insert' and then 'heapify', but it is enough to 'set'
void set(long i, T& elt);
//print
inline friend ostream& operator<<(ostream& s, const pqheap_t1<T> &pq) {
s << "PQ: "; s.flush();
for (unsigned int i=0; i< mymin(10, pq.cur_elts); i++) {
s << "["
//<< pq.elements[i].getPriority() << ","
//<< pq.elements[i].getValue()
<< pq.elements[i]
<< "]";
}
return s;
}
//print
void print();
//print
void print_range();
#ifdef HEAPSTATUS
inline void heapstatus(int d);
inline void heaptouch(unsigned int pos);
unsigned int *numtouch;
#endif
};
//************************************************************/
template <class T>
inline
pqheap_t1<T>::pqheap_t1(unsigned int size) {
elements = new T [size];
cout << "pqheap_t1: register memory\n";
cout.flush();
PQHEAP_MEM_DEBUG cout << "pqheap_t1::pq_heap_t1: allocate\n";
// PQHEAP_MEM_DEBUG MMmanager.print();
if (!elements) {
cerr << "could not allocate priority queue: insufficient memory..\n";
exit(1);
}
assert(elements);
max_elts = size;
cur_elts = 0;
#ifdef HEAPSTATUS
numtouch = new unsigned int[size/PAGESIZE];
assert(numtouch);
for(int i=0; i<size/PAGESIZE; i++) {
numtouch[i] = 0;
}
#endif
}
//************************************************************/
/* (this constructor is a bit nasty) Build heap from an array of
elements; array a is reused, and not copied, for efficiency; it'd
better not be used after this outside!!! */
template <class T>
inline
pqheap_t1<T>::pqheap_t1(T* a, unsigned int size) {
{
static int flag = 0;
if(!flag) {
cerr << "Using slow build in pqheap_t1" << endl;
flag = 1;
}
}
elements = a;
max_elts = size;
cur_elts = size;
if (max_elts) {
for (int i = heap_parent(max_elts-1); i>=0; i--) {
//cout << "heapify i=" << i<<"\n";
heapify(i);
}
}
}
//************************************************************/
template <class T>
inline
pqheap_t1<T>::~pqheap_t1() {
#ifdef HEAPSTATUS
cout << endl << "pagesize = " << PAGESIZE << endl;
cout << "max_elts = " << max_elts << endl;
unsigned int n = max_elts / PAGESIZE;
for(unsigned int i=0; i<n; i++) {
cout << form("PQTEMP %d\t%d", i, numtouch[i]) << endl;
}
delete [] numtouch;
#endif
delete [] elements;
cur_elts = 0;
max_elts = 0;
return;
}
//************************************************************/
//build a heap from an array of elements;
//if size > max_elts, insert first maxsize elements from array;
//return nb of elements that did not fit;
template <class T>
inline unsigned int
pqheap_t1<T>::fill(T* a, unsigned int size) {
unsigned int i;
assert(cur_elts == 0);
for (i = 0; i<size; i++) {
if (!insert(a[i])) {
break;
}
}
if (i < size) {
assert(i == max_elts);
return size - i;
} else {
return 0;
}
}
//************************************************************/
template <class T>
inline bool
pqheap_t1<T>::full(void) {
return cur_elts == max_elts;
}
//************************************************************/
template <class T>
inline bool
pqheap_t1<T>::empty(void) {
return cur_elts == 0;
}
//************************************************************/
template <class T>
inline unsigned int
pqheap_t1<T>::num_elts(void) {
return cur_elts;
}
//************************************************************/
template <class T>
inline bool
pqheap_t1<T>::min(T& elt) {
if (!cur_elts) {
return false;
}
elt = elements[0];
return true;
}
//************************************************************/
template <class T>
T
pqheap_t1<T>::min() {
T elt;
if(min(elt)) {
return elt;
} else {
cerr << "unguarded min failed" << endl;
assert(0);
exit(1);
}
return elt;
}
//************************************************************/
//this function is a dirty hack to allow building faster the heap
//in case we build it from a sorted array; in thiat case we dont need
//to 'insert' and then 'heapify', but it is enough to 'set'
template <class T>
inline void
pqheap_t1<T>::set(long i, T& elt) {
//must always set precisely the next element
assert(i == cur_elts);
elements[i] = elt;
cur_elts++;
}
//************************************************************/
#ifdef HEAPSTATUS
template <class T>
inline void pqheap_t1<T>::heaptouch(unsigned int pos) {
numtouch[pos/PAGESIZE]++;
assert(numtouch[pos/PAGESIZE] > 0);
}
#endif
#ifdef HEAPSTATUS
template <class T>
inline void pqheap_t1<T>::heapstatus(int d) {
static int count = 0;
static int delta = 0;
delta += d;
count++;
if((count % 10000) == 0) {
cout << endl << form("PQHEAP %d\t%d", cur_elts, delta) << endl;
count = 0;
delta = 0;
}
}
#endif
//************************************************************/
template <class T>
inline bool
pqheap_t1<T>::extract_min(T& elt) {
if (!cur_elts) {
return false;
}
elt = elements[0];
elements[0] = elements[--cur_elts];
heapify(0);
#ifdef HEAPSTATUS
heaptouch(cur_elts);
heaptouch(0);
heapstatus(-1);
#endif
return true;
}
//************************************************************/
//extract all elts with min key, add them and return their sum
template <class T>
inline bool
pqheap_t1<T>::extract_all_min(T& elt) {
T next_elt;
bool done = false;
//extract first elt
if (!extract_min(elt)) {
return false;
} else {
while (!done) {
//peek at the next min elt to see if matches
if ((!min(next_elt)) ||
!(next_elt.getPriority() == elt.getPriority())) {
done = true;
} else {
extract_min(next_elt);
elt = elt + next_elt;
}
}
}
return true;
}
//************************************************************/
template <class T>
inline bool
pqheap_t1<T>::delete_min() {
T dummy;
return extract_min(dummy);
}
//************************************************************/
template <class T>
inline bool
pqheap_t1<T>::insert(const T& elt) {
unsigned int ii;
if (full()) {
return false;
}
for (ii = cur_elts++;
ii && (elements[heap_parent(ii)].getPriority() > elt.getPriority());
ii = heap_parent(ii)) {
elements[ii] = elements[heap_parent(ii)];
}
elements[ii] = elt;
#ifdef HEAPSTATUS
heaptouch(ii);
heapstatus(+1);
#endif
return true;
}
//************************************************************/
template <class T>
inline void
pqheap_t1<T>::heapify(unsigned int root) {
unsigned int min_index = root;
unsigned int lc = heap_lchild(root);
unsigned int rc = heap_rchild(root);
#ifdef HEAPSTATUS
// already did the root, so dont do it again
if(lc < cur_elts) {
heaptouch(lc);
}
if(rc < cur_elts) {
heaptouch(rc);
}
#endif
if ((lc < cur_elts) &&
((elements[lc].getPriority()) < elements[min_index].getPriority())) {
min_index = lc;
}
if ((rc < cur_elts) &&
((elements[rc].getPriority()) < elements[min_index].getPriority())) {
min_index = rc;
}
if (min_index != root) {
T tmp_q = elements[min_index];
elements[min_index] = elements[root];
elements[root] = tmp_q;
heapify(min_index);
}
}
//************************************************************/
//Delete the current minimum and insert the new item;
//the minimum item is lost (i.e. not returned to user);
//needed to optimize merge
template <class T>
inline void
pqheap_t1<T>::delete_min_and_insert(const T &x) {
assert(cur_elts);
elements[0] = x;
heapify(0);
}
/************************************************************/
template <class T>
void pqheap_t1<T>::print() {
cout << "[";
for (unsigned int i=0; i<cur_elts; i++) {
cout << elements[i].getPriority().field1() <<",";
}
cout << "]";
}
/************************************************************/
template <class T>
void pqheap_t1<T>::print_range() {
cout << "[";
T a, b;
min(a);
max(b);
if (cur_elts) {
cout << a.getPriority().field1() << ".."
<< b.getPriority().field1();
}
cout << " (" << cur_elts << ")]";
}
#endif // _PQUEUE_HEAP_H
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