minmax_sort.h

// Copyright (c) 2013 Craig Henderson
// https://github.com/cdmh/sorting_algorithms

#include "sort.h"

namespace cdmh {

// MinMax Sort

template<typename It, typename Pred=std::less<typename std::iterator_traits<It>::value_type>>
inline void minmax_sort(It begin, It end, Pred pred=Pred())
{
    auto count = std::distance(begin, end);
    for (auto it=begin, ite=end; count > 1; ++it, count-=2)
    {
        auto minmax = std::minmax_element(it, ite, pred);
        std::advance(ite,-1);

        if (minmax.second == it  &&  minmax.first == ite)
            std::swap(*it, *ite);
        else if (minmax.second == it)
        {
            std::swap(*minmax.second, *ite);
            std::swap(*minmax.first, *it);
        }
        else
        {
            std::swap(*minmax.first, *it);
            std::swap(*minmax.second, *ite);
        }
    }
}

}   // namespace cdmh

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