The case of 5 persons on 6 occasions may be solved as follows:--

1 2 3 4 5

1 2 4 5 3

1 2 5 3 4

---------

1 3 2 5 4

1 4 2 3 5

1 5 2 4 3

Amusements in Mathematics · 第 789 / 970 题