On 2/26/18 10:09 AM, Chris Angelico wrote:
On Tue, Feb 27, 2018 at 2:02 AM, bartc <b...@freeuk.com> wrote:
On 26/02/2018 14:04, bartc wrote:
On 26/02/2018 13:42, Ned Batchelder wrote:
Well, once you notice that the
Python code had N=1e5, and the C code had N=1e9 :) If you want to
experiment, with N=1e5, the final number should be 5255210926702073855.
OK, I'll try that.
I have that Python version working now. It's necessary to apply that masking
function to wherever numbers can get bigger.
I don't know how long a 1-billion loop will take, but a 10-million loop took
46 seconds on Python 3.6, and 21 seconds on PyPy 2.7 from a couple of years
ago. (And on Windows, which has a somewhat slower CPython than Linux.)
You're still reimplementing the C code in Python, which is
inefficient. Have you considered going back to the *actual algorithm*
and implementing that idiomatically in Python? I think you'll find
that (a) the code is more readable, and (b) the run time is much
lower.
Don't bother: C will win this kind of race every time.
--Ned.
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