While giving interviews, Interviewers generally asks questions which tests logical thinking of candidate. This is one of the questions I faced while giving Interviews.
There are 2 ways through which you can swipe 2 numbers and it will gives you desired result.
Method 1:
Suppose X = 20 and Y = 10
Pseudo code for this is:
X = X + Y // Hence, X will be 30 Y = X - Y // Hence, Y will be 20 X = X - Y // Hence, X will be 10
So this will swipe numbers.
Method 2:
Suppose X = 20 and Y = 10
Pseudo code for this is:
X = X + Y - (Y=X);
To elaborate this further, First X+Y will happen that makes things like below:
X = 30 - (Y = X)
Then,
Y = X // Y will be 20
Hence,
X = 30 - 20 = 10