String Permutation Challenge

Problem

Here is another mathematical problem, where the trick is as much to discover the algorithm as it is to write the code: write a program to display all possible permutations of a given input string--if the string contains duplicate characters, you may have multiple repeated results. Input should be of the formpermute string
and output should be a word per line.

Here is a sample for the

input 

catcat 

cta 

act 

atc 

tac 

tca

Solution

#include <iostream>

#include <string>

using namespace std;

string swtch(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(swtch(topermute, place, nextchar),

        place+1);

}

}

int main(int argc, char* argv[])

{

if(argc!=2)

{

cout<<"Proper input is 'permute string'";

                return 1;

}

        permute(argv[1], 0);

}