n playing cards some turned up and some turned down
Source: All - Russian Regional Olympiad (Round 4) 1993 9.4
August 26, 2024
combinatorics
Problem Statement
We have a deck of playing cards, some of which are turned up and some are turned down. In each step we are allowed to take a set of several cards from the top, turn the set and place it back on the top of the deck. What is the smallest number of steps necessary to make all cards in the deck turned down, independent of the initial configuration?