47. Silent Breakfast Briefings
Two known robbers are being tailed by two plain-clothes police officers 24 hours a day. Every morning the four of them go to the same diner for breakfast.
The thieves arrive, hang up their hats and coats on the cloak-room rack, sit at opposite ends of the counter, eat in silence, put their things back on and leave.
They never speak, never exchange notes, and make no obvious gestures—yet the criminals manage to pass detailed information to one another every single day without the policemen realising it.
How are the robbers communicating?
Added 29 January 2012
Hint: Look closely at what happens to their hats and coats while they are eating.
Solution:
Before sitting down, the first robber encodes his message by choosing specific hooks on the cloak-room rack and by the order or orientation in which he hangs his hat and coat (for example, hook numbers 3-14-5 could represent the letters C-N-E).
The second robber notes the exact positions while the police think nothing of it. When the meal is over, he re-hangs the garments on different, pre-agreed hooks to send his reply. Because all the police see is two men hanging up and reclaiming outerwear, the silent exchange of information goes completely unnoticed.
Comments (1)
They wear identical hats and coats, taking each other's on the way out.
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