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Thread: Well, that was fun

  1. Jun 29th, 2004, 11:17 PM #1
    alkatran
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    Well, that was fun

    I just found some programming test asking me to prove if the any even number between 6 and a million is equal to the sum of two prime numbers.

    Well, it's running right now. Outputting to a file. This is the first prime number making proggy I've done so hopefully it works.

    ...The file is now at 19k. and the last number is 28019. Make that 20k...

    Go compy go! Almost 1% done! (It'll slow done more as it approaches a million, right?) Then of course it needs to compare...

    I didn't optimize this code at all. It actually just creates an array of prime numbers and loops through them ALL (^2 since it needs a subloop!)

    Crazy ol me
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  2. Jun 29th, 2004, 11:45 PM #2
    mendhak
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    How are you generating the primes?
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  3. Jun 30th, 2004, 12:44 AM #3
    Foxer
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    There will be 42.

    It's been proven many times before ...
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  4. Jun 30th, 2004, 08:35 AM #4
    Xcoder
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    Originally posted by Gary Campbell
    There will be 42.

    It's been proven many times before ...

    thanks for ruining the surprise...
    Last edited by Xcoder : 09-10-2001 at 12:45 AM.
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  6. Jun 30th, 2004, 05:20 PM #5
    NotLKH
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    Re: Well, that was fun

    Originally posted by alkatran
    I just found some programming test asking me to prove if the any even number between 6 and a million is equal to the sum of two prime numbers.

    3 + 5 = 8
    Proof that there exists an even number between 6 and a million that is the sum of 2 prime numbers.

    You can can your progie now.



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  7. Jun 30th, 2004, 05:28 PM #6
    Foxer
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    So what's the answer?

    I'll use it as a multiplier on the next software project I quote on ...
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  8. Jun 30th, 2004, 06:52 PM #7
    alkatran
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    I had it calculate up to about 100000 before I went to bed. So far the answer is true (there have been tests up to 4*10^14 (maybe higher)).

    I'm generating the primes by creating a list of primes and comparing new numbers against it.

    Basicly, start a dynamic array with 1 element containing 2. Check 3, sesize, put 3 in. Check 5, resize... check 9, 9 is divisible by 3.., don't resize... etc

    BTW, my "incredibly" advanced formula is "If int(x/y) = x/y then it aint no prime"
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  9. Jun 30th, 2004, 08:42 PM #8
    mendhak
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    Great. Your next task is to find the 42nd Mersenne (sp?) prime.

    If [2n-1] is prime, then it is Mersenne.
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  11. Jun 30th, 2004, 11:56 PM #9
    alkatran
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    Error: Overflow
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  12. Jul 1st, 2004, 12:43 AM #10
    Foxer
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    Great. What do I use to quote with now? I've been hanging on that number for days ...

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