“Gata, m-am uitat destul prin magazin, acum trebuie sa cumpar un joc!” se gandeste Petru.

 

A. Joc de societate (10%)

Petru are de ales intre jocul de Domino, Go si Rummy, tinand cont de preferintele celor 4 prieteni ai sai, cu care se va juca.

  1. Fiecare dintre cei 4 prieteni a ordonat cele 3 jocuri (Domino, Go, Rummy) in ordinea preferintei proprii. Fiecare prefera un joc inaintea altuia, deci nu exista 2 jocuri pe care un prieten le prefera in egala masura.
  2. Nu exista 2 prieteni pentru care ordinea preferintelor sa fie identica.
  3. Jocul de domino este a treia preferinta pentru exact 2 dintre prieteni.
  4. 2 jocuri sunt preferinta a doua pentru exact 2 prieteni.
  5. Petru nu tine cont de preferintele sale, ci cumpara jocul preferat de cei mai multi prieteni (jocul care este in topul preferintelor pentru cei mai multi prieteni; in caz de egalitate, atunci tine cont de preferinta a doua a prietenilor sai).   

Ce joc cumpara Petru?

Sursa: problema originală (Ruxandra F. Olimid)

 

“Enough, I looked around too much, I need to buy a game!”  thinks Petru.

 

A. Games (10%)

Petru needs to choose a game: Domino, Go or Rummy, keeping in mind the preferences of his 4 friends, which will be his partners.

  1. Each of his 4 friends sorted the 3 games (Domino, Go, Rummy) by their own preference. Each one prefers one game to another, so there are no games a friend prefers equally.
  2. Each 2 friends have different preferences on games.
  3. Domino is the 3rd preference for exactly 2 friends.
  4. 2 games are the 2nd preference for exactly 2 friends.
  5. Petru does not take into account his own preferences, but buys the game that is preferred by most of his friends (the game that is the 1st preference for most of his friends; if there are more games satisfying this criterion,  then Petru takes into account the 2nd preference of his friends).

 Which game does Petru buy?

Source: original problem (Ruxandra F. Olimid)

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