src/utils/next_combination.hpp

/*
 * Copyright (c) 2005 The University of Notre Dame. All Rights Reserved.
 *
 * The University of Notre Dame grants you ("Licensee") a
 * non-exclusive, royalty free, license to use, modify and
 * redistribute this software in source and binary code form, 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 "AS IS," without a warranty of any
 * kind. All express or implied conditions, representations and
 * warranties, including any implied warranty of merchantability,
 * fitness for a particular purpose or non-infringement, are hereby
 * excluded.  The University of Notre Dame and its licensors shall not
 * be liable for any damages suffered by licensee as a result of
 * using, modifying or distributing the software or its
 * derivatives. In no event will the University of Notre Dame or its
 * licensors be liable for any lost revenue, profit or data, or for
 * direct, indirect, special, consequential, incidental or punitive
 * damages, however caused and regardless of the theory of liability,
 * arising out of the use of or inability to use software, even if the
 * University of Notre Dame has been advised of the possibility of
 * such damages.
 *
 * SUPPORT OPEN SCIENCE!  If you use OpenMD or its source code in your
 * research, please cite the appropriate papers when you publish your
 * work.  Good starting points are:
 *                                                                      
 * [1]  Meineke, et al., J. Comp. Chem. 26, 252-271 (2005).             
 * [2]  Fennell & Gezelter, J. Chem. Phys. 124, 234104 (2006).          
 * [3]  Sun, Lin & Gezelter, J. Chem. Phys. 128, 234107 (2008).          
 * [4]  Kuang & Gezelter,  J. Chem. Phys. 133, 164101 (2010).
 * [5]  Vardeman, Stocker & Gezelter, J. Chem. Theory Comput. 7, 834 (2011).
 */
 
/**
 * @file next_combination.hpp
 * @author    tlin
 * @date  10/27/2004
 * @version 1.0
 */ 

#ifndef UTILS_NEXT_COMBINATION_HPP
#define UTILS_NEXT_COMBINATION_HPP

#include <vector>
#include <iterator>
#include <iostream>
namespace OpenMD {

  /**
   * @brief STL next_permuation-like combination sequence generator.
   * Given the first and last iterator of a sequence, next_combination iteratively generates all 
   * possible combinations.
   * @return if more combination is availiable, otherwise return false
   * @param iterContainer iterator container
   * @param first the first iterator
   * @param last the last iterator
   * @note first and last must be random access iterators and iterContainer must be the container of  
   * random access iterators . And all of the iteratos in iterContainer must be within the range [first, last)
   *
   * @code
   * std::vector<int> iv;
   * iv.push_back(1);
   * iv.push_back(8);
   * std::vector<std::vector<int>::iterator> ic;
   * while(next_combination(ic, iv.begin(), iv.end())) {
   *     for (i =  ic.begin(); i < ic.end(); ++i) {
   *         std::cout << **i << "\t";
   *     }
   *     std::cout << std::endl;
   * }
   * //output
   * //1
   * //8
   * //1  8
   * @endcode
   */
  template<class RandomAccessIterator>
  bool next_combination(std::vector<RandomAccessIterator>& iterContainer, RandomAccessIterator first, RandomAccessIterator last) {
    if (first == last) {
      return false;
    }
    
    RandomAccessIterator endIter = --last;
    typename std::vector<RandomAccessIterator>::iterator i = iterContainer.end();
    
    if (iterContainer.empty()) {
      //if sequence is empty, we insert the first iterator
      iterContainer.insert(iterContainer.end(), first);
      return true;
    } else if (*(--i) != endIter){
      //if the last iterator in iterContainer does not reaches the end, just increase its iterator by 1 
      ++(*i);
      return true;
    } else {// the last iterator in iterContainer does not reaches the end

      //starts at the end of the sequence and works its way towards the front, looking for two 
      //consecutive members of the sequence where the difference between them is greater 
      //than one. For example , if the sequence contains 1, 5, 8, 9 (total number is 10, first is 0
      //and the last is 10 (due to STL's half open range)). At the end of while
      //loop, j will point to 5, and i will point to 8, next combination should be 1, 6, 7, 8.
      //If j is less than zero, it means it already reaches the last combination of current size.
      //For instance, sequence may contain 6, 7, 8, 9 at this time, we need to increase the size
      // of combination to 5
      typename std::vector<RandomAccessIterator>::iterator j = i;
      --j;
      while( j >= iterContainer.begin() && *i == *j + 1){
        --i;
        --j;
      };

      RandomAccessIterator raIter;
      if (j - iterContainer.begin() < 0) { //reaches the last combination of current size
        //half open range
        if (last  - first + 1  == iterContainer.size()) {
          //if the current size equals to total number, done
          return false;
        } else {

          //push the first currentSize+1 element into sequence 
                
          for(i = iterContainer.begin(), raIter= first; i  != iterContainer.end(); ++i, ++raIter) {
            *i = raIter;
          }    
          iterContainer.insert(iterContainer.end(), raIter);
                
          return true; 
        }
            
      } else {
        ++(*j);
        raIter = *j;
        for(; i != iterContainer.end(); ++i) {
          ++raIter;
          *i = raIter;
        }
        return true;
      }
    }
  } //end next_combination

} //end namespace OpenMD
#endif //UTILS_NEXT_COMBINATION_HPP

Revision:	1879
Committed:	Sun Jun 16 15:15:42 2013 UTC (12 years, 4 months ago) by gezelter
File size:	5847 byte(s)
Log Message:	MERGE OpenMD development 1783:1878 into trunk
#	Content
1	/*
2	* Copyright (c) 2005 The University of Notre Dame. All Rights Reserved.
3	*
4	* The University of Notre Dame grants you ("Licensee") a
5	* non-exclusive, royalty free, license to use, modify and
6	* redistribute this software in source and binary code form, provided
7	* that the following conditions are met:
8	*
9	* 1. Redistributions of source code must retain the above copyright
10	* notice, this list of conditions and the following disclaimer.
11	*
12	* 2. Redistributions in binary form must reproduce the above copyright
13	* notice, this list of conditions and the following disclaimer in the
14	* documentation and/or other materials provided with the
15	* distribution.
16	*
17	* This software is provided "AS IS," without a warranty of any
18	* kind. All express or implied conditions, representations and
19	* warranties, including any implied warranty of merchantability,
20	* fitness for a particular purpose or non-infringement, are hereby
21	* excluded. The University of Notre Dame and its licensors shall not
22	* be liable for any damages suffered by licensee as a result of
23	* using, modifying or distributing the software or its
24	* derivatives. In no event will the University of Notre Dame or its
25	* licensors be liable for any lost revenue, profit or data, or for
26	* direct, indirect, special, consequential, incidental or punitive
27	* damages, however caused and regardless of the theory of liability,
28	* arising out of the use of or inability to use software, even if the
29	* University of Notre Dame has been advised of the possibility of
30	* such damages.
31	*
32	* SUPPORT OPEN SCIENCE! If you use OpenMD or its source code in your
33	* research, please cite the appropriate papers when you publish your
34	* work. Good starting points are:
35	*
36	* [1] Meineke, et al., J. Comp. Chem. 26, 252-271 (2005).
37	* [2] Fennell & Gezelter, J. Chem. Phys. 124, 234104 (2006).
38	* [3] Sun, Lin & Gezelter, J. Chem. Phys. 128, 234107 (2008).
39	* [4] Kuang & Gezelter, J. Chem. Phys. 133, 164101 (2010).
40	* [5] Vardeman, Stocker & Gezelter, J. Chem. Theory Comput. 7, 834 (2011).
41	*/
42
43	/**
44	* @file next_combination.hpp
45	* @author tlin
46	* @date 10/27/2004
47	* @version 1.0
48	*/
49
50	#ifndef UTILS_NEXT_COMBINATION_HPP
51	#define UTILS_NEXT_COMBINATION_HPP
52
53	#include <vector>
54	#include <iterator>
55	#include <iostream>
56	namespace OpenMD {
57
58	/**
59	* @brief STL next_permuation-like combination sequence generator.
60	* Given the first and last iterator of a sequence, next_combination iteratively generates all
61	* possible combinations.
62	* @return if more combination is availiable, otherwise return false
63	* @param iterContainer iterator container
64	* @param first the first iterator
65	* @param last the last iterator
66	* @note first and last must be random access iterators and iterContainer must be the container of
67	* random access iterators . And all of the iteratos in iterContainer must be within the range [first, last)
68	*
69	* @code
70	* std::vector<int> iv;
71	* iv.push_back(1);
72	* iv.push_back(8);
73	* std::vector<std::vector<int>::iterator> ic;
74	* while(next_combination(ic, iv.begin(), iv.end())) {
75	* for (i = ic.begin(); i < ic.end(); ++i) {
76	* std::cout << **i << "\t";
77	* }
78	* std::cout << std::endl;
79	* }
80	* //output
81	* //1
82	* //8
83	* //1 8
84	* @endcode
85	*/
86	template<class RandomAccessIterator>
87	bool next_combination(std::vector<RandomAccessIterator>& iterContainer, RandomAccessIterator first, RandomAccessIterator last) {
88	if (first == last) {
89	return false;
90	}
91
92	RandomAccessIterator endIter = --last;
93	typename std::vector<RandomAccessIterator>::iterator i = iterContainer.end();
94
95	if (iterContainer.empty()) {
96	//if sequence is empty, we insert the first iterator
97	iterContainer.insert(iterContainer.end(), first);
98	return true;
99	} else if (*(--i) != endIter){
100	//if the last iterator in iterContainer does not reaches the end, just increase its iterator by 1
101	++(*i);
102	return true;
103	} else {// the last iterator in iterContainer does not reaches the end
104
105	//starts at the end of the sequence and works its way towards the front, looking for two
106	//consecutive members of the sequence where the difference between them is greater
107	//than one. For example , if the sequence contains 1, 5, 8, 9 (total number is 10, first is 0
108	//and the last is 10 (due to STL's half open range)). At the end of while
109	//loop, j will point to 5, and i will point to 8, next combination should be 1, 6, 7, 8.
110	//If j is less than zero, it means it already reaches the last combination of current size.
111	//For instance, sequence may contain 6, 7, 8, 9 at this time, we need to increase the size
112	// of combination to 5
113	typename std::vector<RandomAccessIterator>::iterator j = i;
114	--j;
115	while( j >= iterContainer.begin() && i == j + 1){
116	--i;
117	--j;
118	};
119
120	RandomAccessIterator raIter;
121	if (j - iterContainer.begin() < 0) { //reaches the last combination of current size
122	//half open range
123	if (last - first + 1 == iterContainer.size()) {
124	//if the current size equals to total number, done
125	return false;
126	} else {
127
128	//push the first currentSize+1 element into sequence
129
130	for(i = iterContainer.begin(), raIter= first; i != iterContainer.end(); ++i, ++raIter) {
131	*i = raIter;
132	}
133	iterContainer.insert(iterContainer.end(), raIter);
134
135	return true;
136	}
137
138	} else {
139	++(*j);
140	raIter = *j;
141	for(; i != iterContainer.end(); ++i) {
142	++raIter;
143	*i = raIter;
144	}
145	return true;
146	}
147	}
148	} //end next_combination
149
150	} //end namespace OpenMD
151	#endif //UTILS_NEXT_COMBINATION_HPP
152