
Answer :
Two of the pots, 13
and 19, were in their proper places.
As every interchange may result in a pot being put in its place, it is
clear that twentytwo interchanges will get them all in order.
But this number of moves is not the fewest possible, the correct answer
being seventeen.
Exchange the following pairs: (31, 23), (154, 1615), (177, 2017),
(2410, 1124, 1211), (85, 68, 216, 2321, 2223, 1422, 914,
189).
When you have made the interchanges within any pair of brackets, all
numbers within those brackets are in their places.
There are five pairs of brackets, and 5 from 22 gives the number of
changes required : 17.
