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Thread: How would I alter my code?

  1. #1
    Junior Member
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    Default How would I alter my code?

    If my code:

    public void sortArray () {
    int beginP = 0;
    int endP = myArray.length-1;
    while(beginP<endP){
      if((myArray[beginP]!=GREEN) && (myArray[endP]!=BLUE)){
        swap(beginP, endP);
      }
      while((beginP < myArray.length) && (myArray[beginP]==GREEN)){
        beginP++;
      }
      while(myArray[endP]==BLUE){
        endP--;
      }
    }

    produced: G G G B B B B

    how would I alter it so that it would produce: B B B B G G G?



    I feel as though I am missing one step, but I cannot put my finger on it.


  2. #2
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    Default Re: How would I alter my code?

    Alter it how? Why can't you just use the same sorting algorithm and change every BLUE with a GREEN and vice versa?

  3. #3
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    Default Re: How would I alter my code?

    I tried that before, I don't know why that didn't work.

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: How would I alter my code?

    Have you tried debugging the code by adding some println()s to show what is happening?

  5. #5
    Super Moderator helloworld922's Avatar
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    Default Re: How would I alter my code?

    I would recommend implementing a compareTo() method that determines which color comes before which.

    Something like:

    /**
     * Blue comes before green.
     *
     * Returns less than 0 if item1 comes before item2
     * Returns 0 if item1 comes at the same place as item2
     * Returns greater than 0 if item1 comes after item2
     */
    public static int compareTo(ColorItem item1, ColorItem item2)
    {
        int val1 = 0;
        int val2 = 0;
        if(item1 == BLUE)
        {
            val1 = 1;
        }
        else
        {
            val1 = 2;
        }
     
        if(item2 == BLUE)
        {
            val2 = 1;
        }
        else
        {
            val2 = 2;
        }
     
        return val1 - val2;
    }

    Then, somewhere in your code implement a standard sorting algorithm (say, selection sort because it's very easy).