permutation

This is a discussion on permutation within the C++ Programming forums, part of the General Programming Boards category; I didn't have a clue where to start on this help-free challenge. So I examined the solution and then stared ...

  1. #1
    Registered User
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    Dec 2004
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    465

    permutation

    I didn't have a clue where to start on this help-free challenge. So I examined the solution and then stared blankly at it.
    Please explain this:
    Code:
    #include <iostream>
    #include <string>
    
    string switch(string topermute, int x, int y)
    {
    	string newstring = topermute;
    	newstring[x] = newstring[y];
    	newstring[y] = topermute[x]; //avoids temp variable
    	return newstring;
    }
    void permute(string topermute, int place)
    {
    	if(place == topermute.length - 1)
    	{
    		cout<<topermute<<endl;
    	}
    	for(int nextchar = place; nextchar < 
    	    topermute.length(); nextchar++)
    	{
    		permute(switch(topermute, place, nextchar),
    		        place+1);
    	}
    }
    
    int main(int argc, char* argv[])
    {
    	if(argc!=2)
    	{
    		cout<<"Proper input is 'permute string'";
    	}
    	else
    	{
    		permute(argv[1], 0);
    	}
    	return 0;
    }
    My computer is awesome.

  2. #2
    former member Brain Cell's Avatar
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    Sure. Would you like some beer while we explain it to you?
    My Tutorials :
    - Bad programming practices in : C
    - C\C++ Tips
    (constrcutive criticism is very welcome)


    - Brain Cell

  3. #3
    & the hat of GPL slaying Thantos's Avatar
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    Sep 2001
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    5,681
    Nothing to explain as it won't compile:
    Code:
    string switch(string topermute, int x, int y)
    You can't have a function called switch

  4. #4
    Registered User
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    Dec 2004
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    465
    Oh well then tell the webmaster that cause I copy and pasted into the post.
    My computer is awesome.

  5. #5
    Administrator webmaster's Avatar
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    Aug 2001
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    967
    Indeed, I read Thantos's post and have fixed the code on the site.

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