100 boxes, only 50 attempts

Asked Jan 05 '21 at 12:12

Active Jan 05 '21 at 12:21

Viewed 83 times

There are 100 boxes in the room. In every box there is a note with some number from 1 to 100 (no repetitions).Person A comes into the room and checks all the boxes and notes inside them. He can (doesn't have to) choose 2 boxes and swap notes between them. After he finishes he exits the room. Person B comes to the room. He needs to find a note with some random number. In order to do it he can open only 50 boxes.

Question: how person A should switch 2 boxes in order to help person B to find the number? (person A doesn't know which note person B should find).

edited Jan 05 '21 at 12:21

Rand al'Thor

116,845
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asked Jan 05 '21 at 12:12

Miriam

4

Does this answer your question? How to beat Count Dracula (this is actually marked as a duplicate of https://puzzling.stackexchange.com/q/25558/32339 which is very similar to your question) – xhienne Jan 05 '21 at 12:29
This is also essentially the 100 Prisoners' Names in Boxes puzzle, but where person A fixes things to make the solution strategy work in every case. – Jaap Scherphuis Jan 05 '21 at 12:30

100 boxes, only 50 attempts

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