So this is the power of python 2.7

>>59865085

i dont get it.

you traded the memory complexity for time complexity?

>>59865135
This is /g/. Stop expecting these "programmers" to know what memory complexity is. In fact I wouldn't be surprised if he didn't even know what time complexity was :^).

>>59865206
>using the smiley with a carat nose

>>59865085
>he doesn't know about the time command in *nix

>>59865206

>knows what big O is
>thinks he's special

Nice crypto desktop thread

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>>59865263

i do but time added ~0.05 seconds

>>59865230
>>59865277

Thanks for taking the bait gentlemen :^)

>>59865135
Nobody cares about memory complexity anymore

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>>59865206
>takes a discrete math class at community college
>now self declared king of /g/

>>59865353
>retard spotted
People don't care about constant factors on memory usage anymore, but they damn sure care about memory complexity.

>>59865353
People like you are cancer

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>>59865085
please rewrite it in C and glue it with Python

The Sieve of Eratosthenes is pop-maths you should know from high-school, so don't think you can lord over those gamestop employees just yet.

If you're a beginner, then well done. Now learn Lisp.

>>59865368
And honestly, even that's not true. Constant factors are still important, just not fixed costs.

>>59865307
>using the smiley with a carat nose

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>>59865085

Theme music for this thread. Thanks OP you are the hero python 2.7 deserves!

https://www.youtube.com/watch?v=ALZHF5UqnU4&list=RDQMOv95jIhGdkg

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>>59865085
I don't get what this thread is about. But my sieve is faster, and uses less memory.

$ time python3 sieve_of_Eratosthenes2.py 
1075207199997334

real    0m33.612s
user    0m33.572s
sys    0m0.040s

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>>59867716
>python stronk!
Get in the slow lane. A real programming language is driving in the fast lane.

0.842868
1075207199997334
Program ended with exit code: 0

>>59867716
>>59868180

#include <stdio.h>
void main() { 
    printf("1075207199997334\n");
}

>>59868227
>implying
Test the code yourself faggot. Here it is in text form so you can copy/paste. If you even have or know how to operate a C compiler that is.

My time is from a Core i7 MBP using Xcode with optimizations on.

>33s vs. 0.8s
Yeah. Python is that fucking slow.

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <string.h>
#include <time.h>
#define ISBITSET(x, i) (( x[i>>3] & (1<<(i&7)) ) != 0)
#define SETBIT(x, i) x[i>>3] |= (1<<(i&7));
#define CLEARBIT(x, i) x[i>>3] &= (1<<(i&7)) ^ 0xFF;
typedef unsigned long long int lli;

lli sumPrimes(lli n)
{
    lli m = (n-1) / 2;
    lli bsize = m/8+1;
    char* b = (char*)malloc(bsize * sizeof(char));
    lli i = 0;
    lli p = 3;
    lli s = 2;
    lli j;
    
    memset(b, 255, bsize);
    while (p*p < n) {
        if (ISBITSET(b,i)) {
            s += p;
            j = (p*p - 3) / 2;
            while (j < m) {
                CLEARBIT(b, j);
                j += p;
            }
        }
        i += 1; p += 2;
    }
    
    while (i < m) {
        if (ISBITSET(b,i)) {
            s += p;
        }
        i += 1; p += 2;
    }
    
    return s;
}

int main(void)
{
    static double time_consumed = 0;
    clock_t start, end;
    start = clock();
    
    long long ans = sumPrimes(200000000);
    
    end = clock();
    time_consumed += (double)(end - start);
    printf("%f\n", time_consumed / CLOCKS_PER_SEC);
    
    printf("%lld\n", ans);
    return 0;
}

>>59868266
>My time is from a Core i7 MBP using Xcode with optimizations on.
what optimizations?

O1 :
0.675089
O2 :
0.6183089
O3 : 
0.647160

use register keyword with loop variables
Don't use O3 as you code can't be vectorized in any way and contain no recursive call

>#include <math.h>
useless

>char* b = (char*)malloc(bsize * sizeof(char));
>memset(b, 255, bsize);
Timesink, you should put it outside sumprime if you want an accurate time.
also
>what is calloc

>no free
why? You used memset but not free.

You shouldn't use bit-manipulation macros with int if you want to manipulate long long int. It works here but not every times.

>>59868615
>>My time is from a Core i7 MBP using Xcode with optimizations on.
>what optimizations?
Ofast.

>Don't use O3 as you code can't be vectorized in any way and contain no recursive call
Doesn't actually make a difference. Run multiple times at each setting, the variance from run-to-run for a setting is larger than the difference you pasted, and O3 or Ofast is just as likely to be faster on any given run as not.

>>char* b = (char*)malloc(bsize * sizeof(char));
>>memset(b, 255, bsize);
>Timesink, you should put it outside sumprime if you want an accurate time.
It's required to solve the problem so it's part of the time.

>also
>>what is calloc
malloc+memset forces the kernel to allocate the memory. calloc (depending on OS) might only allocate the address space. Page faults during processing would hammer processing time.

>>no free
>why? You used memset but not free.
You are right!

>You shouldn't use bit-manipulation macros with int if you want to manipulate long long int. It works here but not every times.
Another good point.

I must really suck at c

> time ./a.out
Result: 1075207199997334
7.40user 0.08system 0:07.49elapsed 99%CPU

Actually just started reading K&R yesterday

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>>59865085
No, we don't have it in store but I can order it for you.

>>59865085
Console font?

>>59867716
Not bad, but just use the builtin sum at the end there.

print(sum(sieve(2e8)))

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>>59865085

Congrats if you posted in this thread ABOVE this image you are one of the dozens of actual programmers on /g/. If you didn't and you are, better luck next time!

>>59865307
>pretending
Sure thing

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>>59867716

op here, i'm not even mad

>>59868180

OP here, all real programmers respect that C++ is faster than Python

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>>59868180

OP here, fuck you i'm learning C++