Can /prog/ please comment on my code?


class prob3{
   
    static long BigBossPrimeOne;
   
    public static void primeFactor(long n){
    boolean prime = true;
    long n1=0;
    long n2=0;
    for(long i=2;(i<=(n/2))&&(prime!=false);i++)
        if ((n%i)==0){
        prime = false;
        n1=i;
        n2=n/i;   
        }   
    if ((prime==true)&&(n>BigBossPrimeOne))
        BigBossPrimeOne = n;
   
    if (prime==false){
        primeFactor(n1);
        primeFactor(n2);
        }            
    }

    public static void main(String args[]){
 
    primeFactor(600851475143L);
    System.out.println(BigBossPrimeOne);
    }

}

I'm just doing the Euler thing to pass the time and I thought why not post this on /prog/ for some insight.

Using the Java language.

Feel free to give me any advice.

Thanks!

Please don't mind the presentation. It's the first time using Emacs and I was under the clock (did this in 15 minutes).

>>37 Ok, its now converted to Purebasic4.5 and added a CPU speed for speedstep/dynamic mhz detection.

Procedure GetCycleCount():  !RDTSC  
::ProcedureReturn:EndProcedure;
Procedure CPUSPEED(): Protected A.q,B.q: time_fix2:A = GetCycleCount(): Sleep_(100): B = GetCycleCount():While (B-A)<1: Goto time_fix2:Wend: ProcedureReturn (B-A)/100000:EndProcedure;
Define.q n,i=5,s=2,starttime,endtime:OpenConsole():If CountProgramParameters():n.q=Val(ProgramParameter()):Else:n.q=600851475143:EndIf:starttime=GetCycleCount():
While n<>2 And (Not (n%2)) :n=n>>1::Wend:While n<>3 And (Not (n%3)) :n=n/3::Wend:
While ((i*i)<=n) :While n<>i And (Not (n%i)) :n=n/i::Wend:: s=s!2: i=i+s+2:Wend:endtime=GetCycleCount()-starttime:
PrintN(Str(n)):PrintN("Elapsed:"+Str(endtime)+" cycles at speed "+Str(CPUSPEED())+" MHZ"):

>>41
Too bad cause PureBasic is 3 times slower than GCC

Old crap from when I did that problem:

import Prelude hiding (all, filter, takeWhile, last)
import Data.List.Stream
n = 600851475143

primeFactors = [x | x <- [3..floor $ sqrt $ fromIntegral n],
               n `mod` x == 0, isPrime x]

main = print $ last primeFactors

primes :: [Int]
primes = 2 : filter isPrime [3,5..]

isPrime :: Int -> Bool
isPrime n = all ((/=0) . mod n) $ takeWhile (\p -> p*p <= n) primes

% time (for i in `seq 1 1000`; do ./a.out >/dev/null; done)
0,26s user 1,09s system 95% cpu 1,412 total
% time (for i in `seq 1 1000`; do ./3 >/dev/null; done)
32,64s user 2,21s system 90% cpu 38,368 total

JavaScript conversion(which is faster than java unsurprisingly)
n="600851475143",i=5,s=2;start=new Date();
while((n!=2)&&(!(n%2))) n>>=1;;while((n!=3)&&(!(n%3))) n/=3;;
while((i*i)<=n){while((n!=i)&& (!(n%i)))n/=i;;i+=2+(s^=2);}
end=new Date();alert(n+ "Elapsed:"+(end-start)+" ms");

>>40

I think >>39 was joking.

>>45
I think >>38 was too, what with his "cleaner" code being less readable than >>21. Some kind of parody of ENTERPRISE coding standards or something.

>>38
int main() is wrong. it should always be either int main(void) or int main(int argc, char *argv[argc]).

>>46
int main(int argc, char *argv[argc])
That won't work and you should know it.

>>47
*argv[argc] is a null pointer. just saying, faggot.

>>47
It does work. The ANSI/ISO/IEC C standard guarantees it.

>>1
Euler
using the Java language
（　≖‿≖）

>>50

Makes for a more interesting challenge no?

What are you a faggot?

And besides if you ever participated in Euler you'll find that Java ISN'T the most cumbersome and sluggish language used.

>>51
Do you mean to say that you've solved every Euler project in every language conceivable, and have found some to be less efficient than Java?

>>52

derailed deduction

less efficient than Java

I believe that's 80% the programmers fault.

>>52
I can name a few that have no programs you wouldn't be hard pressed to underperform using Java. I'll start with malbolge. Should I go on?

>>52

Wait.

Are you implying that Java is the slowest widely used language?

I will give you the benefit of doubt due to my ignorance on the topic but still hardly believable.

>>51
No, I've solved a dozen or two problems.  Stop assuming, idiot.


include <stdio.h>

int main(void)
{
        unsigned long target = 600851475143L;
        unsigned int i = 1;
        unsigned int x;
        for (i = 1; target > 1; ++i)
        {
                /* already know it ain't divisble by 2, 3, or 5 */
                x = 6*i+1;
                if (0 == target % x)
                {
                        target /= x;
                }
                else
                {
                        x += 4;
                        if (0 == target % x)
                        {
                                target /= x;
                        }
                }
        }
        printf("%u\n", x);
        return 0;
}

project-euler→$ time ./a.out
6857

real    0m0.002s
user    0m0.000s
sys     0m0.004s
project-euler→$

>>53
Hardly derailed. Read >>51 again, they must have used Java as well as some other language in order to come to that conclusion.
In fact, >>51 didn't say “participated in Euler using Java”. His conclusion doesn't follow the rest of his post.
>>54
You're multiple negatives are confusing. What?
>>55
I'm not implying anything. In fact, given the absurd proposal in >>52 that >>51 has done that, I'd be implying the exact opposite if I were to imply at all.

This is the way!

It's not that hard. Here's a naive solution in CL. I like Haskell's ranges, so I decided to implement something similiar...


; euler 10

(defun square (n)
  (* n n))

(defun number-line (a b)
  (let ((numbers
     (make-array 1 :fill-pointer 0 :adjustable t)))
    (do ((i a (1+ i)))
    ((> i b) numbers)
      (vector-push-extend i numbers))))

(defun move-up (item sequence)
  (elt sequence (1+ (position item sequence))))

(defun multiple-p (n b)
  (and (/= n b) (= (mod n b) 0)))

(defun sieve-of-eratosthenes (n)
  (let ((numbers (number-line 2 n)))
    (do ((p 2 (move-up p numbers)))
    ((> (square p) n) numbers)
      (setf numbers (delete-if (lambda (x) (multiple-p x p)) numbers)))))

(defun problem-10 ()
  (reduce #'+ (sieve-of-eratosthenes 2000000)))

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>>64
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also enable you to straighten your hair and then gives it flips, curls or waves what you want
IT JUST GETS BETTER AND BETTER

>>65
You do realize that she talks about pubic hair, don't you?

>>66
You do realize that she talks about general pubic hair, don't you?

>>67
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>>68

oh wow Shii_tchan, why do you remove my [o] and [u] tags inside the [spoiler]?

>>69
I actually like it more.

>>69
WORKS ON MY MACHINE

>>69
Works on my machine. You must not be using Anonix.

>>48
Actually, *argv[argc] is a char.
argv[argc] is a null pointer (for their initial values).

76 Name: Anonymous 2011-02-04 15:51

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>>1
Commented.

/*
class prob3{
   
    static long BigBossPrimeOne;
   
    public static void primeFactor(long n){
    boolean prime = true;
    long n1=0;
    long n2=0;
    for(long i=2;(i<=(n/2))&&(prime!=false);i++)
        if ((n%i)==0){
        prime = false;
        n1=i;
        n2=n/i;   
        }   
    if ((prime==true)&&(n>BigBossPrimeOne))
        BigBossPrimeOne = n;
   
    if (prime==false){
        primeFactor(n1);
        primeFactor(n2);
        }            
    }

    public static void main(String args[]){
 
    primeFactor(600851475143L);
    System.out.println(BigBossPrimeOne);
    }

}
*/

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