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2 knight pieces of the game chess were trying to find their way to freedom, while being tied together with a small rope.
It was so small that it forced them to be placed in adjacent squares at all times, but at least they could keep their standard movement, and the rope forced them to move simultaneously.

Here's the list of moves they can do :

        o..o
oo..oo  o..o
..NN..  .NN.
oo..oo  o..o
        o..o

So yeah ... their movement is like placing dominoes which are touching themselves by the corners.

So now let's talk about the hazardous hazards of the following grid :

  • A yellow block is sticky. If both of the knights land on a yellow square, they get stuck forever.
  • A red block is TNT. It will tear both knights to pieces if one of them steps on it.
  • Other than that, an army of knight-eating ants are appearing on each previously stepped square (it turns dark or whatever). If either knight steps on an adjacent square to one swarmed by ants, both get eaten and it's over.

The goal is to start from the top left corner, and end by touching the bottom right corner. No knight can find himself out of bounds. Good luck.

The grid ... Is that something familiar ? :)

Text :

S : start
F : finish

Y : sticky
R : explosives

S..R....YY....YY....YY.....
....Y.R..YYY..YR....R...R..
.YY.Y..R.R.YYRY..R.YY.YY...
.R.YY.....R.YYY......Y.Y.Y.
..Y.R..YY.RYYY...YYYYR.R.Y.
..YYYYYR.YYR...RYYYY..YYY..
YY..YY....YY.Y..Y..R..R.Y..
RYY.Y..R.R.YRYYYY.RYYY....Y
R..R.R.Y.RYYRYY.YYR...Y.Y.Y
...YYYR.Y.YY.....R.YY.YYY..
.R.R.Y..Y..YY.YY.Y..YYYR...
.Y..Y.R.R.YY.R...Y..R......
.YYYYR...RYR..RY...YYYYY.R.
...Y.YY.YY.YY.RYYY.RY..R...
.RRY..YYR..YRY..RYRYY..R.Y.
..Y..RY....YYY..R....R.Y.YR
.YY..YYRYYY.YRYYYYYYY...Y.Y
.YYRYY..YRYYR.YYR.RR..YYYRY
..YYYY.YYYYR...YY...YRYR...
R..R.YRYRY..YYRR...YYR..Y..
.YYYYYY..YRYRR.YRYYRYYYYYR.
..RY..R..Y.Y.YY.YY...R..Y..
...R.YYYRY...YY.R.YR.YY...
YYY.YYYYYYR.Y.R..YYYY..Y..R
..Y.Y.RY....Y.YYY..RYY.R...
.R.YY..R.YY.R...YY...YYY..F

PS :

Answers may consider the tag (but of course nothing restrains you to code your own solver).
I've built up that maze without any program, and I know that even though I added a ton of walls in order to try to make the solution unique, I believe there would still be dozens (if not hundreds) of paths that would lead to victory.

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  • 1
    $\begingroup$ so we have two possible starting configurations and two possible ending configurations, yes? $\endgroup$ – Jonathan Allan Jul 29 '16 at 23:16
  • 3
    $\begingroup$ Exactly, 1 knight has to step on those squares, and the other has to be in an adjacent square. $\endgroup$ – Anton Jul 29 '16 at 23:22
  • $\begingroup$ By refusing to post a plain text version, you are only slightly inconveniencing people who want to use a computer to solve it, but you are making the puzzle totally inaccessible to vision-impaired people. $\endgroup$ – Peregrine Rook Jul 30 '16 at 20:54
  • $\begingroup$ @PeregrineRook I see... next time, I'll draw textured blocks. $\endgroup$ – Anton Jul 30 '16 at 22:25
10
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Here is a solution

using $22$ moves a solution

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  • 1
    $\begingroup$ Although the list of moves provided in the question isn't quite what I'd have imagined. But I'm glad I got to a knights maze before it had been solved for once :D $\endgroup$ – Jonathan Allan Jul 29 '16 at 23:50
  • $\begingroup$ That solution looks difficult to improve... even though the intended solution would make the knights wander all around the grid. Might as well post it for the fun of it. $\endgroup$ – Anton Jul 30 '16 at 8:00
  • $\begingroup$ I might, at some point, re jig my solver from the previous questions to solve this one optimally and see how well I did - unless someone else does it first... $\endgroup$ – Jonathan Allan Jul 30 '16 at 8:01
  • $\begingroup$ Never mind, my path was actually 20 moves (I accidentally counted the virtual 'start' and 'end' nodes); and there are (spoilers) exactly 3 paths of that length. $\endgroup$ – 2012rcampion Jul 30 '16 at 15:36
  • $\begingroup$ Oh well, at least it shows I didn't use a program :D $\endgroup$ – Jonathan Allan Jul 30 '16 at 15:43

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