opencv/3rdparty/flann/heap.h

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/***********************************************************************
* Software License Agreement (BSD License)
*
* Copyright 2008-2009 Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
* Copyright 2008-2009 David G. Lowe (lowe@cs.ubc.ca). All rights reserved.
*
* THE BSD LICENSE
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*************************************************************************/
#ifndef HEAP_H
#define HEAP_H
#include <algorithm>
using namespace std;
namespace cvflann
{
/**
* Priority Queue Implementation
*
* The priority queue is implemented with a heap. A heap is a complete
* (full) binary tree in which each parent is less than both of its
* children, but the order of the children is unspecified.
* Note that a heap uses 1-based indexing to allow for power-of-2
* location of parents and children. We ignore element 0 of Heap array.
*/
template <typename T>
class Heap {
/**
* Storage array for the heap.
* Type T must be comparable.
*/
T* heap;
int length;
/**
* Number of element in the heap
*/
int count;
public:
/**
* Constructor.
*
* Params:
* size = heap size
*/
Heap(int size)
{
length = size+1;
heap = new T[length]; // heap uses 1-based indexing
count = 0;
}
/**
* Destructor.
*
*/
~Heap()
{
delete[] heap;
}
/**
*
* Returns: heap size
*/
int size()
{
return count;
}
/**
* Tests if the heap is empty
*
* Returns: true is heap empty, false otherwise
*/
bool empty()
{
return size()==0;
}
/**
* Clears the heap.
*/
void clear()
{
count = 0;
}
/**
* Insert a new element in the heap.
*
* We select the next empty leaf node, and then keep moving any larger
* parents down until the right location is found to store this element.
*
* Params:
* value = the new element to be inserted in the heap
*/
void insert(T value)
{
/* If heap is full, then return without adding this element. */
if (count == length-1) {
return;
}
int loc = ++(count); /* Remember 1-based indexing. */
/* Keep moving parents down until a place is found for this node. */
int par = loc / 2; /* Location of parent. */
while (par > 0 && value < heap[par]) {
heap[loc] = heap[par]; /* Move parent down to loc. */
loc = par;
par = loc / 2;
}
/* Insert the element at the determined location. */
heap[loc] = value;
}
/**
* Returns the node of minimum value from the heap (top of the heap).
*
* Params:
* value = out parameter used to return the min element
* Returns: false if heap empty
*/
bool popMin(T& value)
{
if (count == 0) {
return false;
}
/* Switch first node with last. */
swap(heap[1],heap[count]);
count -= 1;
heapify(1); /* Move new node 1 to right position. */
value = heap[count + 1];
return true; /* Return old last node. */
}
/**
* Reorganizes the heap (a parent is smaller than its children)
* starting with a node.
*
* Params:
* parent = node form which to start heap reorganization.
*/
void heapify(int parent)
{
int minloc = parent;
/* Check the left child */
int left = 2 * parent;
if (left <= count && heap[left] < heap[parent]) {
minloc = left;
}
/* Check the right child */
int right = left + 1;
if (right <= count && heap[right] < heap[minloc]) {
minloc = right;
}
/* If a child was smaller, than swap parent with it and Heapify. */
if (minloc != parent) {
swap(heap[parent],heap[minloc]);
heapify(minloc);
}
}
};
}
#endif //HEAP_H