Note: This puzzle cannot be solved on the computer. Draw it out on paper and then solve...

|               |              |
X               X              X
|               |              |
|        |             |       |
X        X             X       X
|        |             |       |

Rules: With a single "line" starting anywhere, pass through each X only once.

Answers can be described (as there is more than one way to do it) or scanned and posted.

  • $\begingroup$ Agreed - this is a duplicate of that question. $\endgroup$ May 11, 2017 at 19:58
  • $\begingroup$ Yes, I guess it is. Sorry about that. I thought I had looked, but not hard enough. Although, I will have to add my own answer to the other question. $\endgroup$ May 11, 2017 at 20:11
  • $\begingroup$ Have you tried folding the paper in half to continue your line after a portal jump? $\endgroup$ May 11, 2017 at 20:11
  • $\begingroup$ I added the answers I remembered to the original post (as mine truly is a duplicate, although slightly different in wording) $\endgroup$ May 11, 2017 at 20:19
  • $\begingroup$ It doesn't seem to be a duplicate. You said (rot13)(gung V arrq gb cnff guebhtu rnpu pncvgny K bayl bapr, ohg V frr n fznyy k.). $\endgroup$ Jul 25, 2020 at 8:37

1 Answer 1


This puzzle cannot be solved. Since you can only pass through an X once, one end of the path must be in each of the three large rectangles, and one end must be outside the overall diagram. Since that's four ends, and a line has only two ends, the puzzle cannot be solved as presented. The referenced duplicate question has as one of its answers a detailed explanation of why it's impossible; a simplified explanation (and the one that I immediately thought of) was included, without diagram, in the story "The Sixteen Keys" in Lord Darcy, a collection of Randall Garret's stories about the eponymous detective.

  • $\begingroup$ Actually it can be solved, but it takes thinking outside the box. I missed that someone else posted the question, but it is doable. $\endgroup$ May 11, 2017 at 20:10
  • $\begingroup$ @ben-NabiyDerush If you have a solution that hasn't already been posted on the linked duplicate question, feel free to post another solution there. $\endgroup$ May 11, 2017 at 20:28
  • $\begingroup$ @GentlePurpleRain - Done. $\endgroup$ May 11, 2017 at 20:36
  • $\begingroup$ @ben-NabiyDerush See my comment on your question. (Cryptography involved) $\endgroup$ Jul 25, 2020 at 8:39

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