MathDB

3

Part of 2018 Turkey Team Selection Test

Problems(1)

Operations on a permutation

Source: Turkey Team Selection Test 2018 P3

3/27/2018
A Retired Linguist (R.L.) writes in the first move a word consisting of nn letters, which are all different. In each move, he determines the maximum ii, such that the word obtained by reversing the first ii letters of the last word hasn't been written before, and writes this new word. Prove that R.L. can make n!n! moves.
combinatoricspermutation