Solved

Swapping 0 and 1s in an array

Posted on 2004-09-28
10
269 Views
Last Modified: 2010-03-31
Hello,

For this assignment i'm doing for class(an interative towers of hanoi), I have an array that will contain 0 and 1s that correspond to the number of the disk that is to be moved. And my question is this:

That array, will initially be intitialized to all 1s, and then it needs to swap all 0s to 1s, and all 1s to 0s, but I can't figure out how to do it. I wrote a method but it just undoes work that it's already done, thus giving me what i start with.

here it is:
public static void  bitSwap(int[] swapArray)
{

for (k=0; k < swapArray.length; k++)
{

       if (swapArray[k] == 0)
              {
                    swapArray[k] = 1;
                    break;
               }
                  
}


for (j=0; j < swapArray.length; j++)
{      
            
            if  (swapArray[j] == 1)
               {      

      swapArray[j] = 0;
      break;
      
                }      


}      
}

As you can see, that does undoes itself.  I know it's EASY but i can't figure it out, any help would be appreciated.

-NeedlessKane
0
Comment
Question by:NeedlessKane
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 5
  • 3
  • 2
10 Comments
 
LVL 92

Accepted Solution

by:
objects earned 50 total points
ID: 12175000
try it in one loop:

for (k=0; k < swapArray.length; k++)
{

       if (swapArray[k] == 0)
       {
             swapArray[k] = 1;
       }
       else
       {
             swapArray[k] = 0;
       }              
}
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 12175001
That's OK in principle, but why break?
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 12175015
for (k=0; k < swapArray.length; k++)
{
      swapArray[k] ^= 1;
}
0
Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 

Author Comment

by:NeedlessKane
ID: 12175099
Ok, Object thanks. lol I can't believe i didn't do that, wow. So easy.
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 12175132
The code i posted is not only more efficient on your processor, but more efficient on your wrists ;-)
0
 
LVL 92

Expert Comment

by:objects
ID: 12175142
No worries, glad I could help :)
Let me know if you have any further questions.
0
 

Author Comment

by:NeedlessKane
ID: 12175170
CEHJ: i tried yours, it's not working for me.  What does the ^= operator do?
0
 
LVL 92

Expert Comment

by:objects
ID: 12175210
> i tried yours, it's not working for me.

So much for effiency on your wrist and processor :-D

> What does the ^= operator do?

Not whats required here ;)
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 12175214
>>CEHJ: i tried yours, it's not working for me.  

Why not?

>>What does the ^= operator do?

Performs a bitwise operation on the number to turn 1s into 0s and 0s into 1s
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 12175289
My code works perfectly well, as the following shows:

            int[] swapArray = new int[10];
            for (int k=0; k < swapArray.length; k++) {
                  swapArray[k] = Math.random() > 0.5? 1: 0;
            }

            // Before
            System.out.println(MyArrays.toString(swapArray));
            for (int k=0; k < swapArray.length; k++)
            {
                        swapArray[k] ^= 1;
            }
            // After
            System.out.println(MyArrays.toString(swapArray));


      ....
      

                  static class MyArrays {
                        public static String toString(int[] array) {
                              StringBuffer sb = new StringBuffer();
                              sb.append("[");
                              for (int k=0; k < array.length - 1; k++) {
                                    sb.append(array[k]).append(", ");
                              }
                              sb.append(array[array.length - 1]).append("]");
                              return sb.toString();
                        }
                  }



Producing when i ran it:

[0, 1, 1, 0, 0, 0, 1, 0, 0, 1]
[1, 0, 0, 1, 1, 1, 0, 1, 1, 0]
0

Featured Post

Get 15 Days FREE Full-Featured Trial

Benefit from a mission critical IT monitoring with Monitis Premium or get it FREE for your entry level monitoring needs.
-Over 200,000 users
-More than 300,000 websites monitored
-Used in 197 countries
-Recommended by 98% of users

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

INTRODUCTION Working with files is a moderately common task in Java.  For most projects hard coding the file names, using parameters in configuration files, or using command-line arguments is sufficient.   However, when your application has vi…
Introduction This article is the first of three articles that explain why and how the Experts Exchange QA Team does test automation for our web site. This article explains our test automation goals. Then rationale is given for the tools we use to a…
Viewers learn about the “for” loop and how it works in Java. By comparing it to the while loop learned before, viewers can make the transition easily. You will learn about the formatting of the for loop as we write a program that prints even numbers…
This tutorial covers a step-by-step guide to install VisualVM launcher in eclipse.

726 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question