#include <functional>
#include <algorithm>
#include <iterator>
template< typename BidirectionalIterator, typename Compare >
void quick_sort( BidirectionalIterator first, BidirectionalIterator last, Compare cmp ) {
if( first != last ) {
BidirectionalIterator left = first;
BidirectionalIterator right = last;
BidirectionalIterator pivot = left++;
while( left != right ) {
if( cmp( *left, *pivot ) ) {
++left;
} else {
while( (left != right) && cmp( *pivot, *right ) )
--right;
std::iter_swap( left, right );
}
}
--left;
std::iter_swap( pivot, left );
quick_sort( first, left, cmp );
quick_sort( right, last, cmp );
}
}
template< typename BidirectionalIterator >
inline void quick_sort( BidirectionalIterator first, BidirectionalIterator last ) {
quick_sort( first, last,
std::less_equal< typename std::iterator_traits< BidirectionalIterator >::value_type >()
);
}

SOURCE