I've hacked something together for that now, and after realising that I can't count (even using fingers) it works.

OMG I'm could kick myself!

I missed 18!

Project 14 is my next victim

I've done 1, 2, 5, 6, 7, 8, 9 and 17 now

That's (almost) my level of error! (8-p)

I have NEARLY got Ackermann done

Only real problem is its VERY slow as instead of using recursion it uses the stack

Might use a stopwatch for it actually to see just how long it takes!

Nice one!

Could you explain how you did it if you ever get it done?

I can't understand how to do it without using recursion.

using a stack, by pushing/popping values until you get to the end, call stack would get STUPIDLY high otherwise, as in over 200,000 recursive calls, c# in VS 2008 barfs with stack overflow at 9000 or so

I think C/Java are not suitable languages to solve it in due to the complexity and heavily recursive nature

Having seen how others do it it seems there is a nicer way to do it, as it converges after time
http://www.jstor.org/pss/2323780

Well... 14 has stumped me for now.

I've rewritten it several ways and I keep coming out with the exact same answer.

You should use a BigInteger or similar, largest dataset you can really, thinking about doing it based on bit flags actually as I can have a 256bit number then...

EDIT: did it adapting the algorithm I had to start at 1 million and count down, and to use var instead of a set variable type, seemed to stop the number changing the -ve bit to set it to a huge negative number by mistake and it was pretty quick

But with 14 the numbers aren't ever going to be big enough to warrant that are they?

you would be surprised how big they get and how long the chains go on for (over 500 iterations)

Well, that explains why my answer was wrong then

Reworking it now.

Done problem 10 now. Although I think my answer was too complex, I'm sure I'd be able to re do it a lot more simply.

I'm stopping for a while because I have my exam on Thursday and apparently they are able to send the test this time

Well I've gone back today and had a look at a few more.

Some of them I thought were insanely impossible when I was looking at them previously but today I've rattled through several of them.

So far I've done...

1, 2, 5, 6, 7, 8, 9, 10, 17, 19, 22, 28, 42 and 79.

79 I was able to solve by hand in under a minute.

22 and 42 were very similar with only a couple of changes required.

19 was easy also as the code we use at work has a date data type with all the associated methods.

28 was also not too hard once I realised a pattern.

For some reason I've only just discovered this; will have a play with it this evening (don't fancy trying to do it in an Excel Macro )