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Thread: Bubble Sort Help

  1. #1
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    Default Bubble Sort Help

    Hi everyone,

    I'm trying to do a bubble sort where it takes the largest element and takes it to the right. It works for the most part, but then for some reason the right-most element (after the sorting) becomes 0 and then it acts accordingly. It happens sometimes with arrays, so I don't really know why that is. Here are my bubblesort, swapping, and display codes:

        public void bubblesort()
        {
            int out,in;
     
            for(out=n;out>1;out--)
            {
                for(in=0;in<out;in++)
                {
                    if(a[in]>a[in+1])
                    {
                        swap(in,in+1);
                    }
                    display();
                }
            }
        }

        public void display()
        {
            for(int j=0;j<n;j++)
            {
                System.out.print(a[j] + " ");
            }
            System.out.println();
            System.out.println();
        }

        public void swap(int one,int two)
        {
            long temp=a[one];
            a[one]=a[two];
            a[two]=temp;
        }


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Bubble Sort Help

    Can you make a small complete program that compiles, executes and shows the problem?
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
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    Default Re: Bubble Sort Help

    Sure thing:

    /*
     * To change this template, choose Tools | Templates
     * and open the template in the editor.
     */
    package array;
     
    /**
     *
     * @author ashwin
     */
    public class Array 
    {
        public long[] a;
        public int n;
     
        public Array(int max)
        {
            a=new long[max];
            n=0;
        }
     
        public void insertelement(int value)
        {
            a[n]=value;
            n++;
        }
     
        public void display()
        {
            for(int j=0;j<n;j++)
            {
                System.out.print(a[j] + " ");
            }
            System.out.println();
            System.out.println();
        }
     
        public void bubblesort()
        {
            int out,in;
     
            for(out=n;out>1;out--)
            {
                for(in=0;in<out;in++)
                {
                    if(a[in]>a[in+1])
                    {
                        swap(in,in+1);
                    }
                    display();
                }
            }
        }
     
        public void swap(int one,int two)
        {
            long temp=a[one];
            a[one]=a[two];
            a[two]=temp;
        }
    }

    Main Class:
    /*
     * To change this template, choose Tools | Templates
     * and open the template in the editor.
     */
    package array;
     
    /**
     *
     * @author ashwin
     */
    public class ArrayApp 
    {
        public static void main(String[] args)
        {
            int m=15000;
            Array arr=new Array(m);
     
            arr.insertelement(10);
            arr.insertelement(15);
            arr.insertelement(14);
            arr.insertelement(-5);
            arr.insertelement(10);
            arr.insertelement(1);
            arr.insertelement(43);
            arr.insertelement(27);
            arr.insertelement(33);
            arr.insertelement(6);
            arr.insertelement(8);
            arr.insertelement(39);
     
            System.out.print("Original array: ");
            arr.display();
            System.out.println();
            System.out.println();
     
            arr.bubblesort();
     
            System.out.print("New Array: ");
            arr.display();
        }
    }

    Output:
    run:
    Original array: 10 15 14 -5 10 1 43 27 33 6 8 39 
     
     
     
    10 15 14 -5 10 1 43 27 33 6 8 39 
     
    10 14 15 -5 10 1 43 27 33 6 8 39 
     
    10 14 -5 15 10 1 43 27 33 6 8 39 
     
    10 14 -5 10 15 1 43 27 33 6 8 39 
     
    10 14 -5 10 1 15 43 27 33 6 8 39 
     
    10 14 -5 10 1 15 43 27 33 6 8 39 
     
    10 14 -5 10 1 15 27 43 33 6 8 39 
     
    10 14 -5 10 1 15 27 33 43 6 8 39 
     
    10 14 -5 10 1 15 27 33 6 43 8 39 
     
    10 14 -5 10 1 15 27 33 6 8 43 39 
     
    10 14 -5 10 1 15 27 33 6 8 39 43 
     
    10 14 -5 10 1 15 27 33 6 8 39 0 
     
    10 14 -5 10 1 15 27 33 6 8 39 0 
     
    10 -5 14 10 1 15 27 33 6 8 39 0 
     
    10 -5 10 14 1 15 27 33 6 8 39 0 
     
    10 -5 10 1 14 15 27 33 6 8 39 0 
     
    10 -5 10 1 14 15 27 33 6 8 39 0 
     
    10 -5 10 1 14 15 27 33 6 8 39 0 
     
    10 -5 10 1 14 15 27 33 6 8 39 0 
     
    10 -5 10 1 14 15 27 6 33 8 39 0 
     
    10 -5 10 1 14 15 27 6 8 33 39 0 
     
    10 -5 10 1 14 15 27 6 8 33 39 0 
     
    10 -5 10 1 14 15 27 6 8 33 0 39 
     
    -5 10 10 1 14 15 27 6 8 33 0 39 
     
    -5 10 10 1 14 15 27 6 8 33 0 39 
     
    -5 10 1 10 14 15 27 6 8 33 0 39 
     
    -5 10 1 10 14 15 27 6 8 33 0 39 
     
    -5 10 1 10 14 15 27 6 8 33 0 39 
     
    -5 10 1 10 14 15 27 6 8 33 0 39 
     
    -5 10 1 10 14 15 6 27 8 33 0 39 
     
    -5 10 1 10 14 15 6 8 27 33 0 39 
     
    -5 10 1 10 14 15 6 8 27 33 0 39 
     
    -5 10 1 10 14 15 6 8 27 0 33 39 
     
    -5 10 1 10 14 15 6 8 27 0 33 39 
     
    -5 1 10 10 14 15 6 8 27 0 33 39 
     
    -5 1 10 10 14 15 6 8 27 0 33 39 
     
    -5 1 10 10 14 15 6 8 27 0 33 39 
     
    -5 1 10 10 14 15 6 8 27 0 33 39 
     
    -5 1 10 10 14 6 15 8 27 0 33 39 
     
    -5 1 10 10 14 6 8 15 27 0 33 39 
     
    -5 1 10 10 14 6 8 15 27 0 33 39 
     
    -5 1 10 10 14 6 8 15 0 27 33 39 
     
    -5 1 10 10 14 6 8 15 0 27 33 39 
     
    -5 1 10 10 14 6 8 15 0 27 33 39 
     
    -5 1 10 10 14 6 8 15 0 27 33 39 
     
    -5 1 10 10 14 6 8 15 0 27 33 39 
     
    -5 1 10 10 6 14 8 15 0 27 33 39 
     
    -5 1 10 10 6 8 14 15 0 27 33 39 
     
    -5 1 10 10 6 8 14 15 0 27 33 39 
     
    -5 1 10 10 6 8 14 0 15 27 33 39 
     
    -5 1 10 10 6 8 14 0 15 27 33 39 
     
    -5 1 10 10 6 8 14 0 15 27 33 39 
     
    -5 1 10 10 6 8 14 0 15 27 33 39 
     
    -5 1 10 6 10 8 14 0 15 27 33 39 
     
    -5 1 10 6 8 10 14 0 15 27 33 39 
     
    -5 1 10 6 8 10 14 0 15 27 33 39 
     
    -5 1 10 6 8 10 0 14 15 27 33 39 
     
    -5 1 10 6 8 10 0 14 15 27 33 39 
     
    -5 1 10 6 8 10 0 14 15 27 33 39 
     
    -5 1 6 10 8 10 0 14 15 27 33 39 
     
    -5 1 6 8 10 10 0 14 15 27 33 39 
     
    -5 1 6 8 10 10 0 14 15 27 33 39 
     
    -5 1 6 8 10 0 10 14 15 27 33 39 
     
    -5 1 6 8 10 0 10 14 15 27 33 39 
     
    -5 1 6 8 10 0 10 14 15 27 33 39 
     
    -5 1 6 8 10 0 10 14 15 27 33 39 
     
    -5 1 6 8 10 0 10 14 15 27 33 39 
     
    -5 1 6 8 0 10 10 14 15 27 33 39 
     
    -5 1 6 8 0 10 10 14 15 27 33 39 
     
    -5 1 6 8 0 10 10 14 15 27 33 39 
     
    -5 1 6 8 0 10 10 14 15 27 33 39 
     
    -5 1 6 0 8 10 10 14 15 27 33 39 
     
    -5 1 6 0 8 10 10 14 15 27 33 39 
     
    -5 1 6 0 8 10 10 14 15 27 33 39 
     
    -5 1 0 6 8 10 10 14 15 27 33 39 
     
    -5 1 0 6 8 10 10 14 15 27 33 39 
     
    -5 0 1 6 8 10 10 14 15 27 33 39 
     
    New Array: -5 0 1 6 8 10 10 14 15 27 33 39

  4. #4
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    Default Re: Bubble Sort Help

    Quote Originally Posted by Norm View Post
    Can you make a small complete program that compiles, executes and shows the problem?
    I was able to see my mistake; it was that I iterated n from 0 to out, instead of out-1 because arrays start at 0. I can still post my code, if you would like me to so I can help others that make the same mistake.

  5. #5
    Super Moderator Norm's Avatar
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    Default Re: Bubble Sort Help

    Glad you got it working.
    Thanks for sharing your code.
    If you don't understand my answer, don't ignore it, ask a question.

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