Okay. Not doing any more coding tonight. I've run into something I don't know how to do and need to think about for a while. And just as I've typed that I've realised I need to sort the elements of an array. Which is a lot simpler than how I'd originally set about finding the solution with a multidimensional array.
But I'm still not gunna do it until tomorrow. I need to get some work done on my lines.