Problem 220

[miodrag.milenkovic]

I think it should be specified whether the instructions are read left to right or the other way around (I'm guessing it's left to right, but who knows?)

[elendiastarman]

Does a computer read from right to left?

It's left to right, and you could look between the first sequences and the graph and determine which way it is anyway.

[miodrag.milenkovic]

To answer your question, a machine will do whatever you ask it to, if you look at the assembly instruction set for your machine you won't find any references to right and left, these notions come into existence when memory contents are mapped to an IO device. And if you're in an Arabic speaking country, you may well be asking it to read right to left.

But the question is not particularly relevant, because it is I, a human, who is reading the statement of the problem. And even though English text is read left to right, certain mathematical expressions are meant to be read the other way around, such as composition of operators, e.g. A B C, if A, B, C are operators, usually means "apply C, then B, then A". And L, R, F look like operators to me.

I may have spent too much ink answering a rude reply, but it's written in hope that the more you learn, the more civilized you become.

[elendiastarman]

I did not mean to be rude. Anyway, even if you're in an Arabian country, the problem example should clarify which way it is (as well as the language it's written....hmm...I wonder how the sequence would be interpreted in Arabian countries...hmm...).

[ImRe]

I think, D_n 3 * 2ⁿ - 2 steps long, which will be somewhat longer than 10¹¹. I.e., if we try to do 10¹² steps, then we will fall off at the end.

Am I mixing up something here, or there is a mistake in the problem description?

[hk]

No there is no mistake in the description. Perhaps you missed the 50 in D₅₀
 

[ImRe]

Oops, silly typo in my code. Sorry

[quick.dudley]

D1 = "FaRbFR",
For the purpose of this problem: should D1 be considered 4 steps long or 6? In other words; In the fully expanded sequence: do "a" and "b" contribute towards the step count?
--edit
The above would be 2 steps: "F" is considered 1 step and everything else is 0.

[vlad_tepesch]

My program solves the test case but the answer to the actual problem is not accepted.
can someone please post some reference values (position, orientation) between test and problem case?

Edit:
never mind
Found the bug: the final step in the testcase (abortion due to step count) caused to insert a wrong result in the memoization tables that then was used in the real calculations