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Thread: Need Help With this problem

  1. #1
    Junior Member
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    Mar 2014
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    Default Need Help With this problem

    A twin prime is a prime number that differs from another prime number by exactly 2. For
    example, 3 and 5 are twin primes, since 3 and 5 are each prime and differ by 2
    (likewise, 5 and 7 are also twin primes).
    Complete the twins() method, which takes an integer argument n and prints all the
    sets of twin primes that are less than n, one pair per line. The method does not return
    any value. For example, twins(15) would print
    (3, 5)
    (5, 7)
    (11, 13)
    Use the sieve() method from Part 1 to generate the initial list of prime numbers.

    This is what I have:
    public static void twins (int max)
    ArrayList<Integer> twins= sieve(max);
    new ArrayList<Integer>(max);
    int index = 0;
    for (index = 0; twins.size() - 1 > index; index++)
    if (twins.get(index+1) - twins.get(index) == 2)
    System.out.println(twins.size()+","+ twins.size());
    Last edited by ik1dxD; March 14th, 2014 at 02:41 AM.

  2. #2
    Super Moderator
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    Jun 2013
    So. Maryland, USA
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    Default Re: Need Help With this problem

    Welcome to the Forum! Please read this topic to learn how to post code correctly and other useful tips for newcomers.

    Please post your code correctly. What do you need help with? Please ask a specific question so that we know where to start and that you want something other than someone to just complete your code for you.

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