8 Queens

This is a discussion on 8 Queens within the Contests Board forums, part of the Community Boards category; , but you failed to write the function to the appropriate declaration of BOOL Solution(unsigned hyper solution_to_check);...

  1. #31
    Malum in se abachler's Avatar
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    , but you failed to write the function to the appropriate declaration of

    BOOL Solution(unsigned hyper solution_to_check);
    Until you can build a working general purpose reprogrammable computer out of basic components from radio shack, you are not fit to call yourself a programmer in my presence. This is cwhizard, signing off.

  2. #32
    aoeuhtns
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    Unsigned hyper? What's a hyper? :-) An unsigned long will do just fine; you only need 24 bits to represent solutions somewhat naively, a long long if you represent very naively.
    There are 10 types of people in this world, those who cringed when reading the beginning of this sentence and those who salivated to how superior they are for understanding something as simple as binary.

  3. #33
    Frequently Quite Prolix dwks's Avatar
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    > Unsigned hyper? What's a hyper? :-)
    If you type "unsigned hyper" into google, you can find this: http://www.freesoft.org/CIE/RFC/1832/8.htm
    dwk

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  4. #34
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    >> but you failed to write the function to the appropriate declaration of
    BOOL Solution(unsigned hyper solution_to_check);

    When did you ever say that that was the appropriate declaration?
    Code:
    BOOL Solution(unsigned hyper solution_to_check)
    {	
    	int i, j, Queens[8];
    	for (i = 0; i < 8; i++)
    	{
    		Queens[i] = ((solution_to_check >> (i * 3)) & 7) + (i * 8);
    	}
    	for (i = 0; i < 8; i++)
    	{
    		for (j = 0; j < i; j++)
    		{
    			// Same row
    			if ((Queens[i] / 8) == (Queens[j] / 8))
    				return false;
    
    			// Same column
    			if (((Queens[i] - Queens[j]) &#37; 8) == 0)
    				return false;
    
    			// Diagonally
    			if (abs((Queens[i] / 8) - (Queens[j] / 8)) == abs((Queens[i] % 8) - (Queens[j] % 8)))
    				return false;
    		}
    
    		for (j = i + 1; j < 8; j++)
    		{
    			// Same row
    			if ((Queens[i] / 8) == (Queens[j] / 8))
    				return false;
    
    			// Same column
    			if (((Queens[i] - Queens[j]) % 8) == 0)
    				return false;
    
    			// Diagonally
    			if (abs((Queens[i] / 8) - (Queens[j] / 8)) == abs((Queens[i] % 8) - (Queens[j] % 8)))
    				return false;
    		}
    	}
    	return true;
    }
    Brute force (which is still boring):
    Code:
    for (unsigned long x = 0; x < 16777216; x++)
    {
    	if (Solution(x))
    	{
    		for (i = 0; i < 8; i++)
    			printf("(%d,%d) ", i + 1, ((x >> (3 * i)) & 7) + 1);
    		printf("\n");
    		SolutionCount++;
    	}
    }
    Last edited by Brad0407; 06-22-2007 at 09:24 PM.
    Don't quote me on that... ...seriously

  5. #35
    Frequently Quite Prolix dwks's Avatar
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    >> but you failed to write the function to the appropriate declaration of
    BOOL Solution(unsigned hyper solution_to_check);

    When did you ever say that that was the appropriate declaration?
    Umm, it's your contest, you should be able to choose the appropriate declaration.

    Besides, BOOL and unsigned hyper are probably very unportable . . .
    dwk

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  6. #36
    VA National Guard The Brain's Avatar
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    If you want to see 8 queens, why not just go see a Sigfried & Roy show 4 times tee-hee
    Last edited by The Brain; 06-24-2007 at 09:45 AM.
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  7. #37
    Malum in se abachler's Avatar
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    Quote Originally Posted by Brad0407 View Post
    >> but you failed to write the function to the appropriate declaration of
    BOOL Solution(unsigned hyper solution_to_check);

    When did you ever say that that was the appropriate declaration?
    right here -
    Quote Originally Posted by abachler View Post
    Code:
    x = 0;
    while(!solution(x)) x++;
    now you just need to write the BOOL solution() function and have it return whether X is a valid solution.
    granted I only specified that the function return type BOOL (a.k.a. bool and very portable), but with the possible number of solutions to check being in some cases larger than the maximum value of a 32bit unsigned , it should be obvious that you need x to be hyper, a.k.a. __int64, _int64 , int64 all very portable.
    Until you can build a working general purpose reprogrammable computer out of basic components from radio shack, you are not fit to call yourself a programmer in my presence. This is cwhizard, signing off.

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