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Reversing Integer, Magic Squares, and LCM problems

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Join Date: Oct 2004

Posts: 6

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Eclipse

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Reversing Integer, Magic Squares, and LCM problems

Oct 29th, 2004

Hello. I'm currently a 10th grader who's been sitting in front of the computer for hours trying to figure this assignment out. First, my teacher gave me a reverse integer problem. He wants us to reverse the numbers 12345, 10001, 1200, and 5, and display in in the output. The leading zeros can be omitted. I got the method down here (for the first integer):

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//initialize
int tmpInt1 = 0;

while(tmpInt1 == 12345)
{
newInt *= 10;
newInt += tmpInt1 % 10;
tmpInt1 /= 10;
}

However, there seems to be a problem displaying it in the output, which looks like this:

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FunLoops fun = new FunLoops();
System.out.println("12345 reversed ---> " + fun.reverse(12345));

That's just the first reverse integer, and I am clueless on how to add the other numbers in. Should I use a nested loop? If so, how should I use it? After I figure this out, I still need to do the LCM and the Magic Square part, which is even more complicated. I'm glad I have a 4-day weekend, so this isn't that urgent. But I still need the help. Can someone please show me the correct way to do this? Thank you all so much!!!

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Join Date: Sep 2004

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Narue

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Re: Reversing Integer, Magic Squares, and LCM problems

Oct 29th, 2004

>I got the method down here (for the first integer):
Why not write it generally for all integers?

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
public int reverse_integer ( int val )
{
  int ret = 0;
 
  while ( val != 0 ) {
    ret = 10 * ret + ( val % 10 );
    val /= 10;
  }
 
  return ret;
}
public int reverse_integer ( int val )
{
  int ret = 0;

  while ( val != 0 ) {
    ret = 10 * ret + ( val % 10 );
    val /= 10;
  }

  return ret;
}

>I am clueless on how to add the other numbers in.
It's easiest just to call reverse for each number, provided that reverse can handle any integer intelligently:

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
System.out.println("12345 reversed ---> " + fun.reverse(12345));
System.out.println("12345 reversed ---> " + fun.reverse(10001));
System.out.println("12345 reversed ---> " + fun.reverse(1200));
System.out.println("12345 reversed ---> " + fun.reverse(5));
System.out.println("12345 reversed ---> " + fun.reverse(12345));
System.out.println("12345 reversed ---> " + fun.reverse(10001));
System.out.println("12345 reversed ---> " + fun.reverse(1200));
System.out.println("12345 reversed ---> " + fun.reverse(5));

I'm here to prove you wrong.

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Join Date: Oct 2004

Posts: 6

Reputation: Eclipse is an unknown quantity at this point

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Eclipse

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Re: Reversing Integer, Magic Squares, and LCM problems

Oct 30th, 2004

Thank you, Narue! This portion of the program is working now!

Hopefully, I'm not asking too much, but there's just one last thing I need, and that is how to figure out the LCM of two numbers. I don't really know how to approach it. Should it be best if I stick with using a while loop, compare the two integers, and increment it until it finds the LCM, or should I do something else?

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Join Date: Sep 2004

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Narue

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Code Goddess

Re: Reversing Integer, Magic Squares, and LCM problems

Oct 30th, 2004

Calculating the least common multiple is trivial if you have a routine to find the greatest common divisor:

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
public int lcm ( int a, int b )
{
  return a * b / gcd ( a, b );
}
public int lcm ( int a, int b )
{
  return a * b / gcd ( a, b );
}