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Hyper threading means each physical core acts as two logical cores.



lim = 1,000,000
threads = 32
time = 418 seconds
triplets = 163714
threads = 16
...

Thanks for that one, it reduced the 100,000 time from 25.5 seconds to 16.4 seconds. Next thing I will try is threading. I have 8 usable cores, so how does 16 or 24 Threads sound (i7 3770 @ 3.4 GHz...

Well, I've got the run-time for a lim of 100,000 down from 35.5 seconds to 24-25 seconds with a few tweaks I found, Like the maximum value of a that contains any triplets at all approaches lim/2.

...

Unfortunately, your hypothesis isn't correct. I ran the algorithm such that a+b+c<=1,000,000 but a <= 10,000 to save time. Here's the output:



a = 2000 ; tot = 2993 ; Time = 14.277 sec.
a =...

I'm trying to work through problem 251 on Project Euler. Problem 251 - Project Euler

I've got a working algorithm with a few shortcuts while maintaining 100% accuracy. However, it isn't fast...