
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.
