## Puzzle 163 (Double Back) [Alternator]

This is a Saturday Double Back puzzle, with a twist. The path alternates between visiting a colored region once and visiting twice. Equivalently, if we have two rooms A and B such that there is a segment from A to B, then one of A and B is visited once and one of A and B is visited twice. (in particular these rules imply exactly one third of the rooms in this puzzle is visited twice)

Puzzle 163

Not supposed to be a 12… just a 1 and a 2.

Currently I am at the MIT Mystery Hunt 2010, which will take up my entire weekend (24 hours a day every day). As this post shows I have every intention of keeping up with the posting on this blog still by taking some time off. But if somehow I drop the ball in the next couple of days, you will know why. I have no intention to though; it hasn’t happened for four months now.

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### 7 Responses to “Puzzle 163 (Double Back) [Alternator]”

1. Alan Curry Says:

One of the easiest puzzles this week

2. MellowMelon Says:

Darn. I hit a lot of roadblocks in my testsolves, so I wonder if I missed some tricks here. If I make this variation again I will be sure to make it extra challenging just for you. Thanks for the comment.

3. yy Says:

Within this week I would probably place it on Thursday or Friday, but this was a pretty easy week. On its own I would rate it on the easy side of intermediate, Wednesday, but only because I would add some amount of difficulty rating to new variations, due to the need to understand what the rules mean.

The general solving process of these puzzles is the same as the regular variations. There are a few differences, though I think it balances out easier for the variation.

An interesting challenge would be to create one grid layout which is solvable with either set of rules. I suspect that such a grid, if it is possible, would be easier with the regular version.

4. Cy Reb, Jr. Says:

5. MellowMelon Says:

The answer is just the closed loop specified in the rules… although I am curious as to how you got that and wonder if I missed something. (The solution didn’t seem to spell it out in my eyes…)

I guess this would have been a good opportunity to put in a Mystery Hunt gimmick, but time wasn’t on my side.

6. Cy Reb, Jr. Says:

I was joking, of course. But the 1 has three shapes visited once and the 2 has two shapes visited twice. So onE + tWo = EW.

7. MellowMelon Says:

Oh, very clever. Yes, I definitely have that kind of mindset during the hunt too.

Next year I should try to prepare in advance one or two puzzles with hidden answers for release on these days.