Java Problem/Puzzle

Okay, so I was in a lecture last week, and my teacher was talking about a question she got asked on the spot in a job interview. It's been bugging me ever since. It was something along the lines of;

Say you had two integer variables. How would you switch the values WITHOUT creating a temporary variable?

Can anyone figure out the solution? It's got something to do with arithmetic I believe.

 

You're right about it being arithmetic. You can do something like this.

Code:

[FONT=monospace]
[/FONT]variableOne = [FONT=monospace][/FONT]variableOne + variableTwo;[FONT=monospace]
[/FONT]variableTwo = [FONT=monospace][/FONT]variableOne - variableTwo;
[FONT=monospace][/FONT]variableOne = [FONT=monospace][/FONT]variableOne [FONT=monospace]-[/FONT] variableTwo;

 

XOR is usually used for swapping without a temporary variable rather than addition/subtraction because it's a far less expensive operation and can be used on a wider variety of datatypes.

If you're really curious: http://en.wikipedia.org/wiki/XOR_swap_algorithm

 

Thanks for the replies! I'm kicking myself I didn't figure out the first method. I'd have never guessed the second.