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CodeBlocksPortable/Borland/BCC55/Examples/StdLib/nthelem.cpp

117 lines
3.6 KiB
C++

#include "stlexam.h"
#pragma hdrstop
/**************************************************************************
*
* nthelem.cpp - Example program for rearranging a collection based on nth
* element. See Class Reference Section
*
***************************************************************************
*
* (c) Copyright 1994, 1998 Rogue Wave Software, Inc.
* ALL RIGHTS RESERVED
*
* The software and information contained herein are proprietary to, and
* comprise valuable trade secrets of, Rogue Wave Software, Inc., which
* intends to preserve as trade secrets such software and information.
* This software is furnished pursuant to a written license agreement and
* may be used, copied, transmitted, and stored only in accordance with
* the terms of such license and with the inclusion of the above copyright
* notice. This software and information or any other copies thereof may
* not be provided or otherwise made available to any other person.
*
* Notwithstanding any other lease or license that may pertain to, or
* accompany the delivery of, this computer software and information, the
* rights of the Government regarding its use, reproduction and disclosure
* are as set forth in Section 52.227-19 of the FARS Computer
* Software-Restricted Rights clause.
*
* Use, duplication, or disclosure by the Government is subject to
* restrictions as set forth in subparagraph (c)(1)(ii) of the Rights in
* Technical Data and Computer Software clause at DFARS 252.227-7013.
* Contractor/Manufacturer is Rogue Wave Software, Inc.,
* P.O. Box 2328, Corvallis, Oregon 97339.
*
* This computer software and information is distributed with "restricted
* rights." Use, duplication or disclosure is subject to restrictions as
* set forth in NASA FAR SUP 18-52.227-79 (April 1985) "Commercial
* Computer Software-Restricted Rights (April 1985)." If the Clause at
* 18-52.227-74 "Rights in Data General" is specified in the contract,
* then the "Alternate III" clause applies.
*
**************************************************************************/
#include<algorithm>
#include<vector>
#ifdef _RW_STD_IOSTREAM
#include <iostream>
#else
#include <iostream.h>
#endif
template<class RandomAccessIterator>
void quik_sort(RandomAccessIterator start, RandomAccessIterator end)
{
#ifndef _RWSTD_NO_NAMESPACE
using std::distance;
using std::nth_element;
using std::swap;
#endif
size_t dist = 0;
distance(start, end, dist);
//
// Stop condition for recursion.
//
if(dist > 2)
{
//
// Use nth_element to do all the work for quik_sort.
//
nth_element(start, start+(dist/2), end);
//
// Recursive calls to each remaining unsorted portion.
//
quik_sort(start, start+(dist/2-1));
quik_sort(start+(dist/2+1), end);
}
if(dist == 2 && *end < *start)
swap(start, end);
}
int main ()
{
#ifndef _RWSTD_NO_NAMESPACE
using namespace std;
#endif
//
// Initialize a vector using an array of integers.
//
int arr[10] = {37, 12, 2, -5, 14, 1, 0, -1, 14, 32};
vector<int,allocator<int> > v(arr+0, arr+10);
//
// Print the initial vector.
//
cout << "The unsorted values are: " << endl << " ";
vector<int,allocator<int> >::iterator i;
for(i = v.begin(); i != v.end(); i++)
cout << *i << ", ";
cout << endl << endl;
//
// Use the new sort algorithm.
//
quik_sort(v.begin(), v.end());
//
// Output the sorted vector.
//
cout << "The sorted values are: " << endl << " ";
for(i = v.begin(); i != v.end(); i++)
cout << *i << ", ";
cout << endl << endl;
return 0;
}