Fast generation of permutations
frodo at sim.no
Wed Jan 25 15:33:48 CET 2006
given a sequence of n elements i need to generate all possible
permutations of length k <= n.
I found an elegant way to do this recursively:
def comb(items, n):
if n==0: yield 
for i in xrange(len(items)):
for cc in comb(items[i+1:],n-1):
However, this is way too slow for my needs. I try to use this to
generate all possible 5 card poker hands, but this takes around 17
seconds on an Athlon 2200. That's a 2 orders of magnitude too slow for
I am familiar with writing Python extensions in C++, but I will not do
this until I am confident that it is the only way to get the speed I need.
Any of you excellent sirs have any suggestions on how I can speed this up?
Please find attached an example script that executes and times the poker
"Any fool can write code that a computer can understand.
Good programmers write code that humans can understand"
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