You will be given a string, containing both uppercase and lowercase alphabets (numbers are not allowed).

You have to print all permutations of string with the added constraint that you can't change the uppercase alphabets positions.

Example: (puNeeTgUlia)

The Java code is given below with appropriate comments

Explanation:

import java. util.*;

class Main {

static Set set = new HashSet ();

static void printPerms (char ch[], int ind) {

//If end of string is reached, add it to set

if (ind==ch. length) {

set. add (new String (ch));

return;

}

for (int i=ind; i
//Only swap if lower case

if ((ch[i]>='a' && ch[i]='a' && ch[ind]<='z'))) {

char t = ch[i];

ch[i] = ch[ind];

ch[ind] = t;

}

printPerms (ch, ind+1);

if ((ch[i]>='a' && ch[i]='a' && ch[ind]<='z'))) {

char t = ch[i];

ch[i] = ch[ind];

ch[ind] = t;

}

}

}

public static void main (String[] args) {

printPerms ("aBbCc". toCharArray (),0);

System. out. println (set);

}

}