Thứ Sáu, 25 tháng 1, 2019

IMO 1963 - Problem 6

Problem: Five students $A,B,C,D$ and $E$ have taken part in a certain competition. Before the competition, two persons $X$ and $Y$ tried to guess the rankings. $X$ thought that the ranking would be $A,B,C,D,E$ and $Y$ thought that the ranking would be $D,A,E,C,B$. At the end, it was revealed that $X$ didn't guess correctly any rankings of the participants , and moreover, didn't guess any of the ordering of pairs of consecutive participants. On the other hand , $Y$ guessed the correct rankings of two participants and the correct ordering of two pairs of consecutive participants. Determine the rankings of the competition.
Solution: The result is $EDACB$
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IMO 1964 - Problem 6

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