Author: José Carlos
Date: 05:50:50 04/10/03
Go up one level in this thread
On April 10, 2003 at 07:44:49, Uri Blass wrote:
>On April 10, 2003 at 07:11:43, Albert Bertilsson wrote:
>
>>On April 10, 2003 at 06:35:07, Uri Blass wrote:
>>
>>>On April 09, 2003 at 23:56:54, Russell Reagan wrote:
>>>
>>>>So...who wants to explain how this works? I don't know how it works, but it
>>>>finds all of the solutions to the 8 queens problem.
>>>>
>>>>#include <stdio.h>
>>>>int v,i,j,k,l,s,a[99];
>>>>void main(void){
>>>>for(s=8;*a-s;v=a[j*=v]-a[i],k=i<s,j+=(v=j<s&&(!k&&!!printf(2+"\n\n%c"-(!l<<!j),"
>>>>#Q"[l^v?(l^j)&1:2])&&++l||a[i]<s&&v&&v-i+j&&v+i-j))&&!(l%=s),v||(i==j?a[i+=k]=0:++a[i])>=s*k&&++a[--i]);
>>>> printf("\n\n");
>>>>}
>>>
>>>I do not understand this code because my C knowledge is not enough.
>>>
>>>What is *a-s
>>>
>>>I understand that j*=v is j=j*v butI do not understand the meaning when * is at
>>>the beginning of the command.
>>>
>>>I never used it.
>>>
>>>Uri
>>The *a means "content of a". a is here regarded as a pointer to an integer, thus
>>it can be interpreted as the number at the adress that a points to.
>>
>>*a is the same as a[0], guess this later is more commonly used.
>>
>>/Regards Albert
>
>I understand now.
>
>I have pointers but I do not use them in that way.
>I also do not have numbers as conditions
>
>I think that it is a bad writing and it is better to write
>(a[0]-s)!=0) because it is more clear and I assume that there is no difference
>in speed because the compiler translate it to the same code.
This is not written for speed, it's written for not being understood! (also fo
being short). That's what obfuscation is all about, kind of a game.
There're obfuscation contest, where contestants have to pick some algorithm
and write the shortest and most obscure code.
I don't like it, but some programmers do ;)
José C.
>I guess that the code starts
>
>s=8
>a[0]-s!=0 so we continue to do the loop
>v=A[j*v]-A[i]=0-0=0
>j=j*v=0
>
>k=i<s
>Again I do not use it without ()
>Does it mean k=(i<s)(I see no meaning for (k=i)<s
>
>I think the way to try to understand it is simply to follow all the varaibles
>manually in the first steps but I am not going to do it now.
>
>Uri
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