21
$\begingroup$

An entry in Fortnightly Topic Challenge #35: Restricted Title 1. Inspired by the title of this xkcd comic.


Snakes ... on a plane ... again ...

This time 2 specimens of a huge unknown type of snakes swallowed a part of the passengers on a plane. Luckily the plane was able to land and all victims were rescued.

Unfortunately the rescue got a bit messy, and now you have to reconstruct the exact position of the 2 snakes at the moment of the landing for the FAA, based on witness statements.

puzzle

  • The markings inside the plane show the ends of both snakes (one red and one yellow).
  • The numbers on the sides show the number of squares in a row or column occupied by the corresponding snake.

You have also some additional information about the snake behavior from a local expert:

  • All parts of a snake must be connected vertically or horizontally.
  • Snakes don't branch.
  • A snake doesn't cross or touch itself or the other snake (not even diagonally).

Disclaimer: No snakes were harmed during the creation of this puzzle. Both specimen are securely stowed away on a train to their new home.

$\endgroup$
22
$\begingroup$

Answer

enter image description here

Step-by-step solution

NOTE: There is a slight error in the red snake, because I miscounted the 13. I'm too lazy to remake these images, so these won't be corrected, sorry. enter image description here
Start of puzzle. Top row is entirely occupied by red. The yellow snake can't turn left or right and must go down 5 rows due to the 1 clues:
enter image description here
Due to snake restrictions we must get to here.
enter image description here
More deductions on the red snake due to row clues.
enter image description here
And now, column clues, leveraging the fact that the 1 numbers don't permit turning around. This lets us fill the 17 row.
enter image description here
Now we must fill the rest of the 13 row:
There are actually 14 squares now. Instead of finishing the row to the end, it should go downwards. We can see this by the 3 column at the end, in conjunction with the 2 row. enter image description here
And then they must go down, filling the side columns:
enter image description here
Red snake complete.
enter image description here
Yellow snake's east end can also use column clues with 1 numbers to get some progress:
enter image description here
We also can see that the leftmost yellow column can be entirely filled too:
enter image description here
This gets us some more progress, this time using 2 numbers similarly to 1 numbers earlier since we now have 2 ends to keep track of:
enter image description here
First very minor lookahead: if the three results in the top track going straight, we are going to collide into the red snake later on. So let's not.
enter image description here
Some more forced snake extension. Also, started on the tail of the airplane using nonogram logic (it must be in one piece due to the 2 above it).
enter image description here
9 in the 3rd row above the wings means that the top end of the left snake is filled up. So it turns up and connects to the real top end:
enter image description here
Actually this is how the 9 resolves as the other columns are already filled.
enter image description here
Now they go up...
enter image description here
Real east end heads straight as the 4 column is done now. The bottom ends must turn inward at least once.
enter image description here
There are two ways that the 9 in the 2nd row up in the wings can resolve. This is the wrong way:
enter image description here
This is the right way.
enter image description here
Now we look at the 18 in the 1st row up in the wings. Similarly if the east end went left once more, we encounter the same contradiction with the 5 column, so we should instead let the west end go right once. Now extend them both:
enter image description here
Oh right yeah that 5 column is already full. So is the 7 column. Therefore:
enter image description here
10 column isn't filled yet, but the left 14 column is. Right 14 column isn't filled yet. Hence to resolve and finish the puzzle:
enter image description here

$\endgroup$
  • 1
    $\begingroup$ I am truly impressed at how little brute forcing you needed to use $\endgroup$ – Lord Farquaad Jun 1 '18 at 21:23
  • 1
    $\begingroup$ There is a minor mistake at the right side of the red snake. $\endgroup$ – Sleafar Jun 1 '18 at 21:26

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.