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Reversible hours (Posted on 2015-12-07) Difficulty: 3 of 5
Even upside down, a bat can continue to use its digital watch, because some hours are the same even when viewed in reverse. For example, this is what happens with 12:21.
Let's call these hours reversible.

What is the shortest interval between two reversible hours?

Source:Rudolpho Korchan.

No Solution Yet Submitted by Ady TZIDON    
Rating: 3.0000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re(2): Colon included / no cheating Comment 4 of 4 |
(In reply to re: Colon included by Dej Mar)

Well the problem didn't say it was a Military Bat.  Only in that case would I allow a leading zero.  Maybe that also explains how the bat learned to tell time - even upside down!

In military time I will accept 01:10 as a valid reversible hour (1:10 AM only.)  It is not preceded by 12:21 (12:21 PM.)

In my opinion you can't have it both ways.

It should be noted that when the military teaches its bats to actually wear watches they will no longer have to adapt to reading them upside down.

Another reading of the problem is that the HOUR itself is reversible.  The example cites the 12 o'clock hour as a reversible hour because it contains 12:21.  If we interpret the problem this way some reversible hours are consecutive.  That is to say: 1 hour apart.

  Posted by Jer on 2015-12-09 11:34:46
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