Re^12: Challenge: Number of unique ways to reach target sum

[Limbic~Region]

fergal,
I had a copy/paste error which was the source of a whole lot of problems originally. I left j as type double and updated the printf() format as ".0f" but your way works too. I also had a missing hyphen from -fomit-frame-pointer which I corrected.

I have run this code on my machine and it finished in 53.5 minutes. I am not really shocked by this but I am impressed. The only optimizations the C code attempts to make is by limiting the number of the 17 trillion different sets it visits. Adding in a cache and some other neat doo-dads could probably blow this 53.5 minutes out of the water - but why bother. That is one of the beauties of Perl. The amount of time it would take to devise a C program to beat the Perl is more than time than it takes the Perl to run. Good Job.

[fergal]

Yeah, I thought about rewriting in C, maybe using glib to get nice hashes and strings. Memory usage would be way smaller and it would be way faster but it wouldn't be much fun to write :)

I just got

fergal@anacreon:~$ time ./lr
14479062751

real    76m17.183s
user    75m32.075s
sys     0m0.764s

fergal@anacreon:~$ time perl make_ways.pl
14479062752

real    37m46.569s
user    37m26.124s
sys     0m1.416s

That's without -march=... and -fomit-doodads.