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Best way to print all possible permutations of a string

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  Best way to print all possible permutations of a string sanket <sanketsharma09@gmail.com> - 2011-11-28 17:46 -0800
    Re: Best way to print all possible permutations of a string Ian Collins <ian-news@hotmail.com> - 2011-11-29 15:01 +1300
      Re: Best way to print all possible permutations of a string sanket <sanketsharma09@gmail.com> - 2011-11-29 00:24 -0800
        Re: Best way to print all possible permutations of a string DDD <1983ddd@gmail.com> - 2011-11-29 20:55 -0800

#11925 — Best way to print all possible permutations of a string

Hi all.

I wrote a program to print all permutations of the letters of a
string. Here are my two implementations

1.

include <iostream>
#include <cstdlib>
using namespace std;

int main(int argc, char ** argv)
{
        if(argc < 2) {cout << "Usage:\na.out <string>"<<
endl;abort();}
        string s(argv[1]);

        for(string::iterator i = s.begin(); i != s.end(); i++)
        {
                for(string::iterator j = s.begin(); j != s.end(); j++)
                {
                        if(j == i) continue;
                        for(string::iterator k = s.begin(); k !=
s.end(); k++)
                        {
                                if(k == j || k == i) continue;
                                for(string::iterator p = s.begin(); p !
= s.end(); p++)
                                {
                                        if(p == k||p == j||p == i)
continue;
                                        cout << *i << *j << *k << *p
<< endl;
                                }
                        }
                }
        }
}

2.

#include <iostream>
#include <algorithm>
#include <cstdlib>
using namespace std;

int main(int argc, char ** argv)
{
        if(argc < 2) {cout << "Usage:\na.out <string>"<<
endl;abort();}
        string s(argv[1]);
        sort(s.begin(), s.end());
        cout << s << endl;
        while(next_permutation(s.begin(), s.end())){cout << s <<
endl;}
        return 0;
}

They seem to be working well, but I was wondering if there was a
better way to implement the same without using the STL function
next_permutation.

Thanks,
Sanket

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#11926

On 11/29/11 02:46 PM, sanket wrote:
> Hi all.
>
> I wrote a program to print all permutations of the letters of a
> string. Here are my two implementations

<snip>

> 2.
>
> #include<iostream>
> #include<algorithm>
> #include<cstdlib>
> using namespace std;
>
> int main(int argc, char ** argv)
> {
>          if(argc<  2) {cout<<  "Usage:\na.out<string>"<<
> endl;abort();}

Calling abort is rather drastic, why not just "return EXIT_FAILURE"?

>          string s(argv[1]);
>          sort(s.begin(), s.end());
>          cout<<  s<<  endl;
>          while(next_permutation(s.begin(), s.end())){cout<<  s<<
> endl;}
>          return 0;
> }
>
> They seem to be working well, but I was wondering if there was a
> better way to implement the same without using the STL function
> next_permutation.

s/STL/standard library/

Why would you want to avoid a library function that does what you want 
to do?

-- 
Ian Collins

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#11935

On Nov 28, 8:01 pm, Ian Collins <ian-n...@hotmail.com> wrote:
> On 11/29/11 02:46 PM, sanket wrote:
>
> > Hi all.
>
> > I wrote a program to print all permutations of the letters of a
> > string. Here are my two implementations
>
> <snip>
>
> > 2.
>
> > #include<iostream>
> > #include<algorithm>
> > #include<cstdlib>
> > using namespace std;
>
> > int main(int argc, char ** argv)
> > {
> >          if(argc<  2) {cout<<  "Usage:\na.out<string>"<<
> > endl;abort();}
>
> Calling abort is rather drastic, why not just "return EXIT_FAILURE"?
>
> >          string s(argv[1]);
> >          sort(s.begin(), s.end());
> >          cout<<  s<<  endl;
> >          while(next_permutation(s.begin(), s.end())){cout<<  s<<
> > endl;}
> >          return 0;
> > }
>
> > They seem to be working well, but I was wondering if there was a
> > better way to implement the same without using the STL function
> > next_permutation.
>
> s/STL/standard library/
>
> Why would you want to avoid a library function that does what you want
> to do?
>
> --
> Ian Collins

I am a newbie and wanted to see if my first implementation is optimal.
I should have asked this,
Is it possible to further optimize my first implementation?

--Sanket

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#11966

On Nov 29, 4:24 pm, sanket <sanketsharm...@gmail.com> wrote:
> On Nov 28, 8:01 pm, Ian Collins <ian-n...@hotmail.com> wrote:
>
>
>
>
>
>
>
>
>
> > On 11/29/11 02:46 PM, sanket wrote:
>
> > > Hi all.
>
> > > I wrote a program to print all permutations of the letters of a
> > > string. Here are my two implementations
>
> > <snip>
>
> > > 2.
>
> > > #include<iostream>
> > > #include<algorithm>
> > > #include<cstdlib>
> > > using namespace std;
>
> > > int main(int argc, char ** argv)
> > > {
> > >          if(argc<  2) {cout<<  "Usage:\na.out<string>"<<
> > > endl;abort();}
>
> > Calling abort is rather drastic, why not just "return EXIT_FAILURE"?
>
> > >          string s(argv[1]);
> > >          sort(s.begin(), s.end());
> > >          cout<<  s<<  endl;
> > >          while(next_permutation(s.begin(), s.end())){cout<<  s<<
> > > endl;}
> > >          return 0;
> > > }
>
> > > They seem to be working well, but I was wondering if there was a
> > > better way to implement the same without using the STL function
> > > next_permutation.
>
> > s/STL/standard library/
>
> > Why would you want to avoid a library function that does what you want
> > to do?
>
> > --
> > Ian Collins
>
> I am a newbie and wanted to see if my first implementation is optimal.
> I should have asked this,
> Is it possible to further optimize my first implementation?
>
> --Sanket

You need an algorithm. And you can choose recursion or not.

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