On Thursday, March 28, 2013 3:06:02 PM UTC+10:30, Dave Angel wrote: > On 03/27/2013 11:00 PM, Eric Parry wrote: > > > On Wednesday, March 27, 2013 6:28:01 PM UTC+10:30, Ulrich Eckhardt wrote: > > >> > > <SNIP the double-spaced garbage that GoogleGroups put in - see > > http://wiki.python.org/moin/GoogleGroupsPython > > > > > > > Thank you for your explanation. > > > I noticed that in this particular puzzle when it ran out of candidates in a > > particular cycle, it then changed the last entry to the next one in line in > > the previous cycle. But I cannot find any code to do this. > > > I was hoping to understand the logic so that I could re-write it in VBA for > > excel which would enable any puzzle to be entered directly. > > > Your comments are a big help especially the double negative aspect. > > > > > > > Are you familiar with recursion? Notice the last line in the function > > r() calls the function r() inside a for loop. > > > > So when r() returns, you're back inside the next level up of the > > function, and doing a "backtrack." > > > > When the function succeeds, it will be many levels of recursion deep. > > For example, if the original pattern had 30 nonzero items in it, or 51 > > zeroes, you'll be 51 levels of recursion when you discover a solution. > > > > If you don't already understand recursion at all, then say so, and one > > or more of us will try to explain it in more depth. > > > > -- > > DaveA
Thank you for that explanation. No, I do not understand recursion. It is missing from my Python manual. I would be pleased to receive further explanation from anyone. Eric. -- http://mail.python.org/mailman/listinfo/python-list
