No problem being late, I didn't call it yet. :)

Tybalt89's solution doesn't qualify, knowing beforehand that you don't need one of the robots wasn't part of my game. With such a reduced branch factor brute forcing is easy.

Though it made me think about

My goal was a general algorithm to solve random robot positions in acceptable time.

And to have a problem hard enough to demonstrate some basic and advanced techniques like branch and bound. The recent triangle challenge was far too lightweight in complexity.

FWIW: The origin of this problem was a game we played at our students union in 2005.

But many people attempted to solve the whole problem class in the meantime and published solutions.

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

UPDATE
Disclaimer: I maybe should write a proper test suite for benchmarking under reproducible conditions.

In reply to Re^2: Challenge: Ricochet Robots (updated) by LanX
in thread Challenge: Ricochet Robots by LanX

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