There is, more or less. Mine, in fact. But it's ugly. It's repetitive. If someone gave me that solution, I would think "this is way too unreadable to ever v

There is, more or less. Mine, in fact. But it's ugly. It's repetitive. If someone gave me that solution, I would think "this is way too unreadable to ever verify its correctness". My mistake was using C++98. I think C++11 would handle this better, but I never got around to trying.