TOT 023 1982 Autumn J1 36 cards game, take 4 each time
Source:
August 18, 2019
combinatoricsgamegame strategy
Problem Statement
There are cards in a deck arranged in the sequence spades, clubs, hearts, diamonds, spades, clubs, hearts, diamonds, etc. Somebody took part of this deck off the top, turned it upside down, and cut this part into the remaining part of the deck (i.e. inserted it between two consecutive cards). Then four cards were taken off the top, then another four, etc. Prove that in any of these sets of four cards, all the cards are of different suits.(A Merkov, Moscow)