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/* |
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* Copyright (C) 2000-2004 Object Oriented Parallel Simulation Engine (OOPSE) project |
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* |
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* Contact: oopse@oopse.org |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public License |
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* as published by the Free Software Foundation; either version 2.1 |
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* of the License, or (at your option) any later version. |
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* All we ask is that proper credit is given for our work, which includes |
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* - but is not limited to - adding the above copyright notice to the beginning |
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* of your source code files, and to any copyright notice that you may distribute |
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* with programs based on this work. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public License |
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* along with this program; if not, write to the Free Software |
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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* |
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*/ |
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/** |
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* @file GenerateCombination.hpp |
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* @author tlin |
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* @date 10/27/2004 |
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* @version 1.0 |
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*/ |
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#ifndef UTILS_GENERATECOMBINATION_HPP |
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#define UTILS_GENERATECOMBINATION_HPP |
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#include <vector> |
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namespace oopse { |
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//this algorithm can be modified to be compatible with STL container |
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//Basically, changes totNum to last iteratir and beginIndex to first iterator, sequence from |
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//a vector<int> to a vector<iterator>, STL compatible version will be committed next time |
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bool next_combination(std::vector<int> sequence, int totNum, int beginIndex = 0) { |
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int endIndex = beginIndex + totNum - 1; |
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int currentSize; |
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currentSize = sequence.size(); |
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if (currentSize == 0) { |
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//if sequence is empty, we push the begin index into it |
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sequence.push_back(beginIndex); |
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return true; |
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} else if (sequence[currentSize - 1] != endIndex) { |
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//if the last element of the sequence does not reach the end index, just increment it |
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sequence[currentSize - 1] ++; |
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return true; |
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} else if (totNum == 1) { |
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//if total number is one, and the last element already reaches the end index |
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return false; |
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} else {// At this point, the sequence contains at least two elements, and the last one already reaches |
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// end index |
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int i; |
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int j; |
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//starts at the end of the sequence and works its way towards the front, looking for two |
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//consecutive members of the sequence where the difference between them is greater |
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//than one. For example , if the sequence contains 1, 5, 8, 9 (total number is 10, begin |
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//index is 0, therefore 9 is the end index, and the current size is 4). At the end of while |
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//loop, j will point to 5, and i will point to 8, next combination should be 1, 6, 7, 8. |
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//If j is less than zero, it means it already reaches the last combination of current size. |
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//For instance, sequence may contain 6, 7, 8, 9 at this time, we need to increase the size |
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// of combination to 5 |
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i = currentSize; |
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j = i - 1; |
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while( j >= 0 && sequence[i] == sequence[j] + 1){ |
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i--; |
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j = i -1; |
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}; |
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if (j < 0) { //reaches the last combination of current size |
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if (currentSize == totNum) { |
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//if the current size equals to total number, done |
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return false; |
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} else { |
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//push the first currentSize+1 element into sequence |
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for(int i = 0; i < currentSize; i++) |
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sequence[i] = beginIndex + i; |
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sequence.push_back(beginIndex + currentSize); |
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return true; |
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} |
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} else { |
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++sequence[j]; |
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for(int k = j + 1; k < currentSize; k++) |
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sequence[k] = sequence[k-1] + 1; |
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return true; |
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} |
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} |
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} |
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} //end namespace oopse |
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#endif //UTILS_GENERATECOMBINATION_HPP |