having difficulty with an exercise!!

[Andy-N]

Im new to java and im having a problem with one of the questions.
Here is the exercise:

Im suppose to write a problem that eccepts a 5-letter word from user
and then it generates all possible three letter words or combinations that can be derived from the 5-letter word.

Please get me started.

[evlich]

Combination and permutation algorithms can be implemented using recursion. Maybe give something like this a shot:

public void permutations(String input, int length, String current, Set<String> answer) {
  if( current.length() == length ) answer.add(current);
  else {
    for(int i = 0; i < input.length; i++) {
      String rest = input.substring(0, i) + input.substring(i+1);
      permutations(rest, lengtht, current+input.charAt(i), answer);
    }
  }
}

After calling permutations your set will be filled with the permutations of the given string that have the given length. I hope this helps to get started.

[prometheuzz]

I think this is more to your liking:

public class Test  {
    public static void main(String[] args) {
        String s = "abcde";
        
        for(int i = 0; i < s.length()-2; i++) {
            String subs = s.substring(i,i+3);
            System.out.println("Getting index "+i+"-"+(i+3)+" from: \""+s+"\", resulting in: \""+subs+"\"");
        }
    }
}

Good luck!