Paloş::Code.Blog()

Following my first attempt, I optimized the scripts and improved on my times considerably. I’m really happy with the outcome considering it was all done with PHP. My faith in this platform is increasing :). Note that I also used a slower computer (a laptop) this timeand I decided to to my own time measuring to exclude the loading of the prime numbers (if you think this is cheating then you can simply run the scripts using the time command).

Results:

php -f google_th_4b.php 

Loading primes... done.
Solving for inputs 25, 129, 139, 1087, 1199…
Found prime number 9256873 in 0.32996106147766 seconds.

php -f google_th_4b.php 

Loading primes... done.
Solving for inputs 7, 17, 41, 541…
Found prime number 7830239 in 0.75763010978699 seconds.

Sources:

google_th_4b_prepare.phps

google_th_4b.phps

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Hey there people! After viewing (and being enticed by) Leonardo’s post (and also Peteris’) I decided to take a shot at this problem… using PHP. That’s right, I wanted to see how fast I can make a PHP script solve this darn thing. Because I (also) wanted to make use of the pregenerated list of primes, I made a preparation script first that downloads a specified amount of 1 million prime numbers chunks and inserts them into an SQLite database for easier (and faster) access from PHP (this script is called google_th_4_prepare.php). I only called this script for just 1 million primes since all numbers I tried fit within that, but you can do more if you want (see the defined constants)! (more…)

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