Standard C++	Library
 		 Copyright 1996, Rogue Wave Software, Inc.

 NAME

   partial_sort	- Templated algorithm for sorting collections of
   entities.

 SYNOPSIS

   #include <algorithm>

   template <class RandomAccessIterator>
   void partial_sort (RandomAccessIterator first,
 		     RandomAccessIterator middle,
 		     RandomAccessIterator last);

   template <class RandomAccessIterator,	class Compare>
   void partial_sort (RandomAccessIterator first,
 		     RandomAccessIterator middle,
 		     RandomAccessIterator last,	Compare	comp);

 DESCRIPTION

   The partial_sort algorithm takes the range [first,last) and places
   the first	middle - first values into sorted order.  The result
   is	that the range	[first,	middle)is sorted like it would be if
   the entire	range [first,last) were sorted.  The remaining
   elements in the range (those	in [middle, last)) are not in any
   defined order.	 The first version of the algorithm uses less
   than (operator<) as the comparison operator for the sort.	 The
   second version uses the comparison	function comp.

 COMPLEXITY

   partial_sort does approximately (last	 - first) * log(middle-first)
   comparisons.

 EXAMPLE

   //
   // partsort.cpp
   //
   #include <vector>
   #include <algorithm>
   #include <iostream.h>

   int main()
    {
     int	d1[20] = {17, 3,  5,  -4, 1, 12, -10, -1, 14, 7,
 		   -6, 8, 15, -11, 2, -2,  18,	4, -3, 0};
      //
      //	Set up a vector.
      //
     vector<int>	v1(d1+0, d1+20);
      //
      //	Output original	vector.
      //
     cout << "For the vector: ";
     copy(v1.begin(), v1.end(),
 	 ostream_iterator<int,char>(cout," "));
      //
      //	Partial	sort the first seven elements.
      //
      partial_sort(v1.begin(), v1.begin()+7, v1.end());
      //
      //	Output result.
      //
     cout << endl << endl << "A partial_sort of seven elements
 			     gives: "
 	  << endl << "	   ";
     copy(v1.begin(), v1.end(),
 	 ostream_iterator<int,char>(cout," "));
     cout << endl;
      //
      //	A vector of ten	elements.
      //
     vector<int>	v2(10, 0);
      //
      //	Sort the last ten elements in v1 into v2.
      //
     partial_sort_copy(v1.begin()+10, v1.end(), v2.begin(),
 		      v2.end());
      //
      //	Output result.
      //
     cout << endl << "A partial_sort_copy of the	last ten elements
 		     gives: "
 	  << endl << "	   ";
     copy(v2.begin(), v2.end(),
 	 ostream_iterator<int,char>(cout," "));
     cout << endl;

     return 0;
    }

   Output :
   For the vector: 17 3 5 -4 1 12 -10 -1	14 7 -6	8 15 -11 2 -2 18 4 -3 0
   A partial_sort of seven elements gives:
        -11 -10 -6 -4 -3	-2 -1 17 14 12 7 8 15 5	3 2 18 4 1 0
   A partial_sort_copy of the last ten elements gives:
       0	1 2 3 4	5 7 8 15 18

 WARNING

   If your compiler does	not support default template parameters, then
   you need to always provide the Allocator template	argument.  For
   instance, you will need to write :

   vector<int, allocator<int> >

   instead of :

   vector<int>

 SEE ALSO

   sort,	stable_sort, partial_sort_copy

 STANDARDS CONFORMANCE
   ANSI X3J16/ISO WG21 Joint C++	Committee