Mega Code Archive
Use stable_partition and partition
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/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << ' ';
}
std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
* - fill values from first to last into the collection
* - NOTE: NO half-open range
*/
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
for (int i=first; i<=last; ++i) {
coll.insert(coll.end(),i);
}
}
using namespace std;
int main()
{
vector<int> coll1;
vector<int> coll2;
INSERT_ELEMENTS(coll1,1,9);
INSERT_ELEMENTS(coll2,1,9);
PRINT_ELEMENTS(coll1,"coll1: ");
PRINT_ELEMENTS(coll2,"coll2: ");
cout << endl;
// move all even elements to the front
vector<int>::iterator pos1, pos2;
pos1 = partition(coll1.begin(), coll1.end(), // range
not1(bind2nd(modulus<int>(),2))); // criterion
pos2 = stable_partition(coll2.begin(), coll2.end(), // range
not1(bind2nd(modulus<int>(),2))); // crit.
// print collections and first odd element
PRINT_ELEMENTS(coll1,"coll1: ");
cout << "first odd element: " << *pos1 << endl;
PRINT_ELEMENTS(coll2,"coll2: ");
cout << "first odd element: " << *pos2 << endl;
}
coll1: 1 2 3 4 5 6 7 8 9
coll2: 1 2 3 4 5 6 7 8 9
coll1: 8 2 6 4 5 3 7 1 9
first odd element: 5
coll2: 2 4 6 8 1 3 5 7 9
first odd element: 1
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