On Thu, 2005-07-14 at 00:47 +1000, Steven D'Aprano wrote: > On Wed, 13 Jul 2005 10:21:19 -0400, rbt wrote: > > > Say I have a list that has 3 letters in it: > > > > ['a', 'b', 'c'] > > > > I want to print all the possible 4 digit combinations of those 3 > > letters: > > > > 4^3 = 64 > > > > aaaa > > abaa > > aaba > > aaab > > acaa > > aaca > > aaac > > ... > > > > What is the most efficient way to do this? > > Efficient for who? The user? The programmer? The computer? Efficient use > of speed or memory or development time?
The CPU > > If you want the fastest runtime efficiency, a lookup table of > pre-calculated values. That is an O(1) operation, and you don't get any > faster than that. > > If you expect to extend the program to arbitrary lists, pre-calculation > isn't practical, so you need an algorithm to calculate permutations (order > matters) or combinations (order doesn't matter). My list is not arbitrary. I'm looking for all 'combinations' as I originally posted. Order does not matter to me... just all possibilities. -- http://mail.python.org/mailman/listinfo/python-list
