perplexus.info :: Logic : From ab to ba

From ab to ba (Posted on 2019-01-17)

Given a string of 2 letters ab, your task is to convert it into ba. You are allowed to add either aa or bb on either side of a current string or into the string, like ab=>abaa=>abbb=>aaabbb=>aaabaabb.
You are also allowed to erase either aa or bb any place like aaabbb=>abbb.
Is it possible? If so, how?

No Solution Yet Submitted by Ady TZIDON

Rating: 3.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)

Solution?

Comment 2 of 2 |

Unless my reasoning is wrong, the task is impossible.

There will always be an a somewhere to the left of a b.

Adding aa or bb cannot change this.

Removing aa or bb from the end cannot change this. You can't really remove the original b without first adding in a bb on its side. So you still have a b on the right side.

Removing aa or bb from the middle can only really remove an aa or bb that was previously added.

Posted by Jer on 2019-01-17 12:10:50

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