You have five coins, apparently alike, but actually of different weights. You also have a two arm scale.

Can you manage to sort the coins in ascending order, using the scale only seven times?

Bonus question: can it be done in fewer weighings?

(In reply to re(2): Solution based on the O-Sort sorting algorithm by Erik O.)

Wikipedia at http://en.wikipedia.org/wiki/Shell_sort, exemplifies the shell sort with spans decreasing as: {1391376, 463792, 198768, 86961, 33936, 13776, 4592, 1968, 861, 336, 112, 48, 21, 7, 3, 1}. I don't find, doing a search for o-sort, any algorithm for doing sorts.

Posted by Charlie on 2004-06-02 13:57:13