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Thread: my assignment..not able to complete it...please help...

  1. #1
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    Default my assignment..not able to complete it...please help...

    Problem statement: Write a program in java, to compute the union of two large sets.(1 million in each set)

    Details: Two sets, A and B, will be provided in the form of two text files 'A.txt' and 'B.txt'. Write a program to read these files into memory, and compute their union. The union of these sets should be written to another file, 'union.txt'. It may be noted that the input sets, A and B, are very large sets containing over a million elements each. Enough thought should be put into the choice of data structures for this program, as it will have a bearing on the efficiency of the program. Also, the design of the program should be well thought out--for example, minimizing the number of passes for reading the input, minimizing the number of times a particular value is computed, etc.

    Deliverables:
    * the code
    * total execution time (measured in terms of CPU time, and not wallclock time)
    * a short design document explaining: (a) the algorithm, and (b) the main data structures, along with a justification for their choice.


  2. #2
    Super Moderator curmudgeon's Avatar
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    Default Re: my assignment..not able to complete it...please help...

    You've posted your assignment but have yet to ask an answerable question. If you have a question that we can answer, please ask it, and please show any code that you've created so far.

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    d4divya2005 (December 7th, 2012)

  4. #3
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    Default Re: my assignment..not able to complete it...please help...

    import java.util.*;
    import java.io.*;
    class assignment{
    public static void main(String args[])
    throws Exception{
    FileReader f1 = new FileReader("c://java/2.txt");
    Scanner src= new Scanner(f1);
    int a[];
    a=new int[1000000];
    int i,j;
    j=0;
    while(src.hasNext())
    {if(src.hasNextInt()){
    i=src.nextInt();
    a[j]=i;

    j++;
    }

    }
    f1.close();
    FileReader f2 = new FileReader("c://java/3.txt");
    Scanner src1= new Scanner(f2);
    int b[];
    b=new int[1000000];
    int k,l;
    l=0;
    while(src1.hasNext())
    {if(src1.hasNextInt()){
    k=src1.nextInt();
    b[l]=k;
    l++;
    }


    }

    f2.close();
    int n=a.length+b.length;
    int c[]=new int[10];
    int p=a.length;
    for(i=0;i<a.length;i++)
    {
    c[i]=a[i];
    }
    for(i=0;i<b.length;i++)
    {
    for(j=0;j<a.length;j++)
    {
    if(b[i]!=c[j])
    {continue;}
    else{if(b[i]==c[j])break;}}
    if(j==10)
    c[p++]=b[i];
    }
    for(i=0;i<n;i++)
    {System.out.println(c[i]);}}}

  5. #4
    Super Moderator Norm's Avatar
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    Default Re: my assignment..not able to complete it...please help...

    Please edit your post and wrap your code with
    [code=java]
    <YOUR CODE HERE>
    [/code]
    to get highlighting and preserve formatting.

    Also provide the questions about the problems you are having.
    If you don't understand my answer, don't ignore it, ask a question.

  6. #5
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    Default Re: my assignment..not able to complete it...please help...

    import java.util.*;
    import java.io.*;
    class assignment{
    public static void main(String args[]) 
    throws Exception{
    FileReader f1 = new FileReader("c://java/2.txt"); 
    Scanner src= new Scanner(f1); 
    int a[];
    a=new int[1000000];
    int i,j;
    j=0;
    while(src.hasNext())
    {if(src.hasNextInt()){
    i=src.nextInt();
    a[j]=i;
     
    j++;
    }
     
    } 
    f1.close();
    FileReader f2 = new FileReader("c://java/3.txt"); 
    Scanner src1= new Scanner(f2); 
    int b[];
    b=new int[1000000];
    int k,l;
    l=0;
    while(src1.hasNext())
    {if(src1.hasNextInt()){
    k=src1.nextInt();
    b[l]=k;	
    l++;
    }
     
     
    }
     
    f2.close();
    int n=a.length+b.length;
    int c[]=new int[10];
    int p=a.length;
    for(i=0;i<a.length;i++)
    {
    c[i]=a[i];
    }
    for(i=0;i<b.length;i++)
    {
    for(j=0;j<a.length;j++)
    {
    if(b[i]!=c[j])
    {continue;}
    else{if(b[i]==c[j])break;}}
    if(j==10)
    c[p++]=b[i];
    }
    for(i=0;i<n;i++)
    {System.out.println(c[i]);}}}


    --- Update ---

    the problem is.. its not printing the union of two arrays.. some problem with the union algorithm for two arrays

  7. #6
    Super Moderator Norm's Avatar
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    Default Re: my assignment..not able to complete it...please help...

    Please edit the post and format the code. Statements should be indented when inside of {}s to show logic levels. All statements should NOT start in the first column.

    . its not printing the union of two arrays
    Please post the program's output, explain what is wrong with it and show what it should be.

    Also you need to post the contents of the input files used for testing.
    If you don't understand my answer, don't ignore it, ask a question.

  8. The Following User Says Thank You to Norm For This Useful Post:

    d4divya2005 (December 7th, 2012)

  9. #7
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    Default Re: my assignment..not able to complete it...please help...

    two files contain million integers.. m not getting the output

  10. #8
    Super Moderator Norm's Avatar
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    Default Re: my assignment..not able to complete it...please help...

    What does the program output?

    Have you tested the code with smaller inputs? Did it work?

    Please edit the post and format the code. Statements should be indented when inside of {}s to show logic levels. All statements should NOT start in the first column.
    If you don't understand my answer, don't ignore it, ask a question.

  11. The Following User Says Thank You to Norm For This Useful Post:

    d4divya2005 (December 7th, 2012)

  12. #9
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    Default Re: my assignment..not able to complete it...please help...

    m sorry... i started java just 2 days back.. m totally new...
    i tried with smaller inouts..but not wrking..i just need a program from union of two arrays...i feel my logic is wrong for the union..

  13. #10
    Super Moderator Norm's Avatar
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    Default Re: my assignment..not able to complete it...please help...

    .i feel my logic is wrong for the union..
    Its better to start the testing with smaller files before trying with large files.
    Did the program work with small files? If so did you try increasing the size of the files to find the smallest size that the program fails with?

    You need to do the following, no one wants to work with unformatted code:

    Please edit the post and format the code. Statements should be indented when inside of {}s to show logic levels. All statements should NOT start in the first column.
    If you don't understand my answer, don't ignore it, ask a question.

  14. #11
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    Default Re: my assignment..not able to complete it...please help...

    int n=a.length+b.length;
     
    int c[]=new int[10];
     
    int p=a.length;
     
     for(i=0;i<a.length;i++)
    {
     c[i]=a[i];
    }
    for(i=0;i<b.length;i++)
    {
       for(j=0;j<a.length;j++)
    {
        if(b[i]!=c[j])
        {continue;}
              else{if(b[i]==c[j])break;}}
         if(j==10)
         c[p++]=b[i];
    }
       for(i=0;i<n;i++)
       {System.out.println(c[i]);}}}


    --- Update ---

    i googled about indenting a program.. i dint know what it was.. i m sorry for that.. m totally new... is my logic right for the union of two arrays a[] and b[]

  15. #12
    Super Moderator Norm's Avatar
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    Default Re: my assignment..not able to complete it...please help...

    is my logic right for the union of two arrays a[] and b[]
    What does the code do with small test input files?

    You need to properly format the code.
    If you don't understand my answer, don't ignore it, ask a question.

  16. #13
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    Default Re: my assignment..not able to complete it...please help...

    its just printing 0000000000

  17. #14
    Super Moderator Norm's Avatar
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    Default Re: my assignment..not able to complete it...please help...

    Please format and post the complete program so it can be tested.
    Also post the small test files used for input.
    If you don't understand my answer, don't ignore it, ask a question.

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