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Thread: How to rearrange an array?

  1. #1
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    Default How to rearrange an array?

    Hey guys, in my journey through java i ran in to a bit of a problem.

    How do i rearrange a array?

    // Enter values to test here 
        String[] s = { "from", "first", "to", "last" }; 
        String w; 
    System.out.println(w);
        // Enter your code here

    How would i rearrange array s, to compile backwards in string w? so it would read "last to first from"?


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    Default Re: How to rearrange an array?

    If all you need is all the elements of the array in reverse order then you can use a reverse loop. A normal loop would start at the first element and iterate until it reaches the last element. A reverse loop starts at the last element and iterates until it reaches the first element.

    On the other hand, if you want to move elements about then you will need to copy element A into a temp variable, copy element B into the position element A was, copy the temp variable into the position element B was.
    Improving the world one idiot at a time!

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    Default Re: How to rearrange an array?

    Since you are "Compiling" into a string, you can just use a reverse loop, like Junky said, and then add the elements one at a time to w. Don't forget to add spaces!

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    Default Re: How to rearrange an array?

    Quote Originally Posted by jjd712 View Post
    How do i rearrange a array?
    Pseudo-code for one possible solution to reverse any array:
    //
    // Reverse elements of an array in-place.
    // No extra memory required.
    // Single loop goes through half of the array.
    //
     
    Define int variables i and j
     
    Set i equal to 0, so it is indexing the first element of the array.
     
    Set j equal to array.length-1, so that it is indexing the last element of the array.
     
    Repeat the following loop as long as i is less than j
    BEGIN LOOP
       Swap array[i] and array[j];
       Increment i;
       Decrement j;
    END LOOP

    Cheers!

    Z
    Last edited by Zaphod_b; October 17th, 2012 at 11:54 AM.

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    Default Re: How to rearrange an array?

    Thanks to everyone that helped. Worked fine!

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