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Re: Speeding up permutations generation

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  Re: Speeding up permutations generation Ian Kelly <ian.g.kelly@gmail.com> - 2015-03-06 10:13 -0700

#87047 — Re: Speeding up permutations generation

On Fri, Mar 6, 2015 at 1:24 AM, Abhiram R <abhi.darkness@gmail.com> wrote:
>
>>
>> A list of 100 elements has approximately 9.33 x 10**157 permutations.
>> If you could somehow generate one permutation every yoctosecond,
>> exhausting them would still take more than a hundred orders of
>> magnitude longer than the age of the universe.
>> --
>> https://mail.python.org/mailman/listinfo/python-list
>
>
> True that :D I may have exaggerated on the number. Let's consider something
> more practically manageable => 50 elements with a 50! permutation.
> Is there a solution now?

That's still infeasible, as others have pointed out. At one
permutation every picosecond, you'll still need 9.6 x 10**44 years.

If the size isn't that important to you and you just want a faster
implementation of permutations, you could try reimplementing it
yourself as a C extension. The stdlib implementation is already
written in C though, so unless you have a better algorithm I doubt
you'll find much room for optimization.

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