On Thu, 3 Mar 2005 15:32:36 -0500, Bill Mill <[EMAIL PROTECTED]> wrote:
>On Thu, 03 Mar 2005 10:52:23 -0800, engsol <[EMAIL PROTECTED]> wrote: >> >> The diagonal constraint is interesting....it seems to affect the number of >> solutions. One surprise, (not being a math major), was that when I let the >> brute force run (forever, it seemed), but without the diagonal >> qualification(s), >> there was maybe 100 solutions. The reson it was a surprise it that years >> ago a programmer used the row-sum, col-sum method to detect and correct >> data errors. He swore it was robust, and 100% reliable. Seems that that >> isn't the case. > >I think that it probably is a decent gut-check for data errors, for >the simple reason that changing one number requires, at a minimum, >three other changes in order to maintain both the row and column sums. >If you have at least a decent data fidelity rate, that is unlikely to >happen, and even if it does, very very unlikely to happen in such a >way that the row and column sums are maintained; especially as the >number of rows and columns grows. > >Better to just do a crc or a hash of the data though. > >Peace >Bill Mill >bill.mill at gmail.com You make a good point Bill, and are entirely correct. I never liked that programmer, and was too hasty in condeming his work...shame on me....I was unfair. BTW, I ran the code you suggested, (I like your approach), after correcting the A cell value (should have 5 vice 3 as I posted). There seems to be 16 solutions, one of which agrees with the puzzle author. I don't fully understand this line of your code: return [(a,b,c) for a in ns for b in ns for c in ns if a + b + c == limit] If the "if" part is true, does it 'trigger' the return? Norm B -- http://mail.python.org/mailman/listinfo/python-list
