一些逻辑训练的谜题:娜塔莎、十二点钟和茶
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>>2024年7月3日6位教师们,阿列克谢、娜塔莎、鲍里斯、安东、王明和功夫老爹希望在各自离校前进行一场...
My hypothesis is this:
When the number of items is even, all random permutations will satisfy.
When the number of items is odd, some permutations will not work.
I'm not sure how to prove it.
E.g.
When n = 2, 2P2 = 2, A-B and B-A are the only permutations, and the clockwise distance is always the same.
When n = 4, 4P4 = 24, at least one pair of items will have the same clockwise distance as the original, such as:
A-B-C-D (original)
A-B-D-C (A-B)
A-C-B-D (A-D)
A-C-D-B (C-D)
A-D-B-C (B-C)
A-D-C-B (A-C)
...
However, when n = 3, this permutation does not work:
A-B-C (original)
A-C-B (no clockwise distance remain the same)
When n = 5, this permutation does not work:
A-B-C-D-E (original)
A-D-B-E-C (no clockwise distance remain the same)
