Ok, currently working on problem 5, using the code below, keep on getting an error regarding an 'unresolved external symbol' and I cannot for the love of Geoff work out why it is giving me this. Have renamed every variable going just incase I was using something that was already named and tried commenting out pretty much everything after the int main() but cannot see what's giving the problem.

Try removing the "using std..." bit and put "using namespace std;" as the line after the include line at the beginning.

Seems ok apart from that though.


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I am here: http://maps.google.com/maps?ll=53.851236,-1.530917

Found the cause, I'd selected the wrong project types when creating the project in VS, set that correctly and everything works.

The function itself isn't working properly mind, but that's a different matter entirely

EdIt: It does if you don't comment out your final print screen of the answer!

Woop!

Done number 81 now!

Runs in about 0.001 seconds

LOL!

13 and 25 done!

Wrote my own set of functions to add numbers together in string form and then used these to work out both of the problems.

Somehow I don't think 1000 digit numbers are covered by 32 bit ints.

Will be working on 82 and 83 tonight. Can solve them both with the same program (ish) but need to write the setup first.

got the start & end digit on 79, just 6 digits to go.... so just 720 (minimum) combinations left

Problem 79 done by 'observation', was reasonably straight forward. Would be quite a lot harder to program I suspect.

OK, I've got a program that will solve problem 14 but becuase it's done at work it doesn't have the capacity to store enough entries for the recursive program.

Will have to re-do it in C++ at home tonight.

See I see that as cheating for a problem like this, the whole idea is to program every problem, doing by observation without thinking the process through completely is a different matter to doing it in code


BigInteger in .net is enough

I wish I were better at maths. I've done a few in Perl, but when it started to talk about prime factors, I get somewhat scared off...

I've got the BigInteger library for C++ at home but wanted to try doing it without using a pre-written library.

I was trying to use it using the string library I've written at work.

It takes strings of any length and can add them together and also divide them by 2.

I'm quite pleased with it

I think I may have to try some these...


... but I think I'll try them in Ada

First one I did I ended up writing my own library before finding out it was covered in System.Numerics

No. 1 done in Ada - after learning how to do it again

Finn, when you said you did 14 and it worked pretty quickly, how quickly did it run?

Also what number type did you use to store the lengths and values?

I'm using a recursive function to store all values in an array but I have to use BigIntegers for the lengths and the values otherwise I get stupid nonsense answers.

Also, even though I'm storing all previously encountered lengths it still takes 74 seconds to run. The function works so that if I was to start at 3 (for example) when it finishes running it would have stored the lengths for 3, 10, 5, 16, 8, 4, 2 and 1 (if I just did 3 that is without doing 2 and 1 before it).

It runs the function 3 million times which on a C2D 2.4GHz should take that amount of time (but I do have iTunes playing music and Safari open at the same time).

The only thing I can think is that taking the time up is BigInteger and when looking through the solution forum they have been able to use longs and unsigned longs but these just don't work for me.

Are there differences that would cause one person's long to be different from another person's?