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[Geeze]

ideone.com
I found this pretty useful if you want to work on problems when on any computer.
Pretty good selection of languages

Briefly about ideone
ideone.com is a... pastebin. But a pastebin like no other on the Internet. More accurate expression would be online mini IDE and debugging tool.

Ideone is an Italian word for great ideas - because ideone.com is a place where your greatest ideas can spring to life.

ideone.com is designed mostly for programmers (but, of course, common plain text can also be uploaded). You can use it to:

    share your code (that's obvious - it is a pastebin, isn't it? ) in a neat way,
    run your code on server side in more than 40 programming languages (number still growing)
    and do it all with your own input data!
    ideone.com also provides free Ideone API which is availabe as a webservice. Its functionality allows you to build your own ideone-like service!
    for logged in users Ideone offers possibility to manage their codes, publish multiple submissions at one go, and more.

All codes can be accessed through convenient hash links. Source code pages provide information about the code and its execution: memory usage, execution time, language and compiler version, code itself, input uploaded by the user, output generated by the program and error messages from compilers and interpreters.

It is in great measure your contribution that this service exists - it is you who share your ideas with us and report bugs and suggestions. We hope it is still going to be like this - as long as this site works! Thank you!

Also I envy python users who have lot bigger number limits, because there's many problems that have those very big numbers(And I don't trust doubles).
I kinda cheated on problem 20 (Find sum of digits in 100!) because int/long max is WAAAAYYY too small. I just calculated 100! using python and used the result as input for java-code.

[Dacke]

If you are using Java, you may find BigInteger helpful:
http://docs.oracle.com/javase/6/docs/api/java/math/BigInteger.html

It gives you an unlimited size for integers and has some prime-stuff built in that is missing in Python:

Immutable arbitrary-precision integers. All operations behave as if BigIntegers were represented in two's-complement notation (like Java's primitive integer types). BigInteger provides analogues to all of Java's primitive integer operators, and all relevant methods from java.lang.Math. Additionally, BigInteger provides operations for modular arithmetic, GCD calculation, primality testing, prime generation, bit manipulation, and a few other miscellaneous operations.

 

[Geeze]

It gives you an unlimited size for integers and has some prime-stuff built

[Moczan]

I think the whole point is in learning this stuff on your own. Many of the problems can be easily solved by using Wolfram Alpha/Mathematica but you won't learn much doing it like that 

[Dacke]

I limit my self to using Python, but I use lots of built in stuff even if it makes certain problems trivial. I also installed a bitarray-library, because Python sucks at big arrays. I guess it has to do with what your personal goals are. My main goal is to become efficient with Python. But if someone else just wants to focus on solving them in any way possible, that's totally fine too.

But if you don't take the time to solve the early problems properly in your language of choice, I think that the later problems will kick your ass. So if you "cheat" using Wolfram Alpha, you will probably be screwed later

[Andy Wolff]

I haven't had time for this since last weekend, but I want to get back to it as soon as I can. I'm doing this not to get a huge number of problems solved, but to write a large number of useful mathematical functions and learn as much as I can, so I haven't been cheating or taking the easy way out (more or less). Problem 18 is taking me longer to solve than it should because I'm trying to solve it in such a way that the same method will work for problem 67


Anyway, good work, everyone. It's good to see so many people doing this

[imaginationac]

I started solving the problems using JavaScript, but wanted to learn CoffeeScript so I'm going back through the ones I've done so far.

[Ashkin]

If you are using Java, you may find BigInteger helpful:
http://docs.oracle.com/javase/6/docs/api/java/math/BigInteger.html

It gives you an unlimited size for integers and has some prime-stuff built in

Do you know if AS3 has an equivalent for this, or should I just use Number?

[Andy Wolff]

You should write methods for adding strings of arbitrary length like I did :s

[Dacke]

@Ashkin: The main thing we use BigInteger for is to store big integers (the other stuff is just a bonus). But AS3 Number can store huge numbers and is much easier to use (because it is a primitive type rather than a class (I think?)). So in fact, Java programmers should be envious of Number

[ham and brie]

@Ashkin: The main thing we use BigInteger for is to store big integers (the other stuff is just a bonus). But AS3 Number can store huge numbers and is much easier to use (because it is a primitive type rather than a class (I think?)). So in fact, Java programmers should be envious of Number

AS3's Number is the same as Java's double. It can't store as many different integer values as Java's long.

[Dacke]

Ah, thank you ham and brie, I was mistaken. I thought that Number was an integer format with max_value=10³⁰⁸; I (foolishly) didn't realize that it was a floating point number. I jumped to the wrong conclusion, because the AS3 documentation recommended using Number over int for big integers (which is horrible advice). I should be more careful when it comes to languages I know so little about.

AS3 Number is a double precision floating point number (FP64) and is therefore somewhat unsuitable for handling integers (it will start to bug out for big numbers and has some nasty side effects). It is the same as double in languages like Java.

But Number is not the same as Java's long. A long in Java is an int64, which has a much lower max_value (~10¹⁹) than a double's max_value (~10³⁰⁸). But in return int64 actually works for big numbers, as it is able store every integer up to it's limit (while Number/double just tries to approximate stuff).

Anyway, back to the actual question: Does AS3 have Big Integer support?
The answer seems to be no, it does not. At least not as a built-in. This is no reason for despair, though. The Project Euler problems were probably created under the assumption that you wouldn't have access to a BigInteger class. The actual challenge (that many of us have circumvented) is to implement your own handling of big integers (like Andy Wolff has)

First off you should probably do some reading on how integers are represented. Then write a simple class that supports what you need. You can have stuff like someBigInt.add(someOtherNumber). Where "someOtherNumber" can be an integer, another BigInt or a string representation of a number. Internally you can store the number as a String (Andy Wolff's approach), but I think you'll get better results if you store it as an array (or list) of unsigned integers (uint).

Or if you don't feel up to the task you can always use someone else's full-fledged BigInt implementation, perhaps this one?
http://kingtut666.wordpress.com/2011/04/19/bigint-in-actionscript-3-0/
(But do note that your own implementation would be much simpler that this one, because you don't need everything that is supported in that library)

[BorisTheBrave]

the AS3 documentation recommended using Number over int for big integers (which is horrible advice).

That's because it can hold more integers than an int can. It does all integers up to 2^53, vs 2^32 for ints. In some circumstances this is handy, but not that many.

[Dacke]

Yes, that's true of course

[paste]

I started trying one of these in order to help out Ashkin, but I think it would be a good tool to maintain/improve my c++ chops. Count me in!

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