#include <utility>
#include <iostream>
#include <cstdlib>

template< typename Ret, typename Last >
Ret random_picker_impl( size_t i, Last&& last )
{
   return std::forward<Last>(last);
}

template< typename Ret, typename First, typename Second, typename ... Rest >
Ret random_picker_impl( size_t i, First&& first, Second&& second, Rest&&... rest )
{
   if( i == 0 )
   {
      return std::forward<First>(first);
   }
   else
   {
      return random_picker_impl<Ret>( i-1, std::forward<Second>(second), std::forward<Rest>(rest)... );
   }
}

template< typename First, typename ... Rest >
First random_picker( First&& first, Rest&&... rest )
{
   size_t index = (sizeof...(rest) + 1) * (std::rand() / double(RAND_MAX));
   return random_picker_impl<First>( index, std::forward<First>(first), std::forward<Rest>(rest)... );
}

int main()
{
   for( int i=0; i<20; ++i )
   {
      auto i = random_picker( 1, 2, 3 );
      std::cout << "chose: " << i << '\n';
   }
}