Hi all, It's great how many different sorts of solutions (or almost solutions) this puzzle has generated. Speedwise, for reference my solution posted above takes about 40 seconds on my 1.8GHz laptop, and the less elegant version (on my webpage linked to in the original post) takes about 15 seconds. It seems to me like surely this problem can be more efficiently solved than that?
My version isn't very Pythonic (it could almost be written in C++ the way I've done it) so I liked the idea of the first solution, but I don't think it can be fixed. I adapted it so that it doesn't use the same number more than once, but it still has some problems. Firstly, it only finds solution ((a op b) op c) op d etc. and won't find (for example (1+2)*(3+4). Secondly, it stores a dictionary value->how to get to value which is fine if you can re-use numbers because one way to get to a given value is as good as another, but sometimes you can get to the same number in two different ways using different numbers, so it misses solutions. Paul: 758 = 8+(5*((2+4)*25)) Arnaud: I haven't had time to play with your solution yet - how quick does it run? My fantasy is that there is a solution that isn't TOO slow where you can just look at the code and go 'Oh yes, of course that works!' and understand it immediately. Maybe that's too much to ask even of Python! ;-) -- http://mail.python.org/mailman/listinfo/python-list
