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## Variable Switch

Logic puzzles require you to think. You will have to be logical in your reasoning.

 Puzzle ID: #49422 Fun: (1.97) Difficulty: (2.31) Category: Logic Submitted By: rob77

You're a computer programmer, and the program you're writing has numeric variables A and B. You need the computer to switch the variables so that the number in variable A becomes variable B, and the number in variable B becomes variable A. Adding a third variable would use more memory though, so how can you do that switch without using another variable? Use commands such as B=B-A to assign a new value to B.

B = A+B
A = B-A
B = B-A

Using an example, if A=5 and B=4:
B = 5+4
A = 9-5
B = 9-4
A is now 4 and B is now 5.

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 royale-ninja Jul 24, 2012 i got it...i solved it by another answer A=B-A B=B-A A=A+B royale-ninja Jul 24, 2012 i got it...i solved it by another answer A=B-A B=B-A A=A+B edoridlo Oct 14, 2013 How about this way? A = A + B B = A - B A = A - B rob77 Jan 08, 2014 This was a real exercise I got in a course. Dezaxa Dec 29, 2014 The smart alec answer is to emply some assembler and use registers, e.g. load location of A to register X load location of B to register Y save X to location of B save Y to location of A