166 lines
4 KiB
C
166 lines
4 KiB
C
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/***********************************************************************
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* Software License Agreement (BSD License)
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*
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* Copyright 2008-2009 Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
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* Copyright 2008-2009 David G. Lowe (lowe@cs.ubc.ca). All rights reserved.
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*
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* THE BSD LICENSE
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*************************************************************************/
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#ifndef OPENCV_FLANN_HEAP_H_
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#define OPENCV_FLANN_HEAP_H_
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#include <algorithm>
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#include <vector>
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namespace cvflann
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{
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/**
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* Priority Queue Implementation
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*
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* The priority queue is implemented with a heap. A heap is a complete
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* (full) binary tree in which each parent is less than both of its
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* children, but the order of the children is unspecified.
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*/
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template <typename T>
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class Heap
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{
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/**
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* Storage array for the heap.
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* Type T must be comparable.
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*/
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std::vector<T> heap;
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int length;
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/**
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* Number of element in the heap
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*/
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int count;
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public:
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/**
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* Constructor.
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*
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* Params:
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* sz = heap size
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*/
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Heap(int sz)
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{
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length = sz;
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heap.reserve(length);
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count = 0;
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}
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/**
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*
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* Returns: heap size
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*/
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int size()
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{
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return count;
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}
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/**
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* Tests if the heap is empty
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*
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* Returns: true is heap empty, false otherwise
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*/
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bool empty()
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{
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return size()==0;
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}
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/**
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* Clears the heap.
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*/
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void clear()
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{
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heap.clear();
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count = 0;
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}
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struct CompareT
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{
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bool operator()(const T& t_1, const T& t_2) const
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{
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return t_2 < t_1;
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}
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};
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/**
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* Insert a new element in the heap.
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*
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* We select the next empty leaf node, and then keep moving any larger
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* parents down until the right location is found to store this element.
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*
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* Params:
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* value = the new element to be inserted in the heap
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*/
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void insert(T value)
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{
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/* If heap is full, then return without adding this element. */
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if (count == length) {
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return;
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}
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heap.push_back(value);
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static CompareT compareT;
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std::push_heap(heap.begin(), heap.end(), compareT);
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++count;
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}
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/**
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* Returns the node of minimum value from the heap (top of the heap).
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*
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* Params:
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* value = out parameter used to return the min element
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* Returns: false if heap empty
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*/
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bool popMin(T& value)
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{
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if (count == 0) {
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return false;
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}
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value = heap[0];
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static CompareT compareT;
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std::pop_heap(heap.begin(), heap.end(), compareT);
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heap.pop_back();
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--count;
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return true; /* Return old last node. */
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}
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};
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}
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#endif //OPENCV_FLANN_HEAP_H_
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