This month's riddle comes from Rani Hod.
Consider a permutation over the numbers 1 through
Let us define a Not all permutations are this easy to sort. The permutation [4 3 2 1 5 13 12 11 10 9 8 7 6], for example, was shown by help from a computer to require at least 8 block moves to be sorted.
This month's riddle is regarding sorting the inverse permutation
[
How many block moves does it take to sort the inverse permutation (as a
function of To demonstrate the correctness of your answer, prove that the number you give is a minimum bound and describe an algorithm that sorts in this number of block moves. |
## List of solvers:Sen Gu (2 September 06:55)Bojan Bašić (6 September 06:30) Sun Yixun (6 September 15:33) Dan Dima (26 September 13:16) Marcos Simões (30 September 04:18) Itsik Horovitz (30 September 19:05) |

Elegant solutions can be submitted to the puzzlemaster at __riddlesbrand.scso.com__.
Names of solvers will be posted on this page. Notify if you don't want
your name to be mentioned.

The solution will be published at the end of the month.

Enjoy!