Coding Interview Question: Swap Variables

April 1, 2016

Question

Given two integers, write a function that swaps them without using any temporary variables.

Once you think that you’ve solved the problem, click below to see the solution.

As always, remember that practicing coding interview questions is as much about how you practice as the question itself. Make sure that you give the question a solid go before skipping to the solution. Ideally if you have time, write out the solution first by hand and then only type it into your computer to verify your work once you've verified it manually. To learn more about how to practice, check out this blog post.

Solution

How was that problem? You can check out the solution in the video below.

Here is the source code for the solution shown in the video:

public void swap(int x, int y) {
    x = x + y;
    y = x - y;
    x = x - y;
}

public void swap(int x, int y) {
    x = x ^ y;
    y = x ^ y;
    x = x ^ y;
}

1

2

3

4

5

6

7

8

9

10

11

public void swap(int x, int y) {

x = x + y;

y = x - y;

x = x - y;

}

public void swap(int x, int y) {

x = x ^ y;

y = x ^ y;

x = x ^ y;

}

Did you get the right answer to this coding interview question? Please share your thoughts in the comments below.

DON'T DO ANOTHER CODING INTERVIEW...

...until you've mastered these 50 questions!

The Definitive Guide to Data Structures for Coding Interviews

Data structures are critical to coding interview success. In this post, I'll show you exactly which data structures you need to know to nail your interviews.

Article

10 ways to get unstuck and never fail another coding interview

It happens time and again. People fail coding interviews because they don’t know what to do when stuck on a problem. Developing a clear plan of attack helps you to succeed at any whiteboard coding interview.