Permutation of an array, with repetition, in Java

Question

There are some similar questions on the site that have been of some help, but I can\'t quite nail down this problem, so I hope this is not repetitive.

This is a home

Answer 1

If I understand correctly, you are given a set of characters c and the desired length n.

Technically, there's no such thing as a permutation with repetition. I assume you want all strings of length n with letters from c.

You can do it this way:

to generate all strings of length N with letters from C
 -generate all strings of length N with letters from C
     that start with the empty string.

to generate all strings of length N with letters from C
   that start with a string S
 -if the length of S is N
  -print S
 -else for each c in C
  -generate all strings of length N with letters from C that start with S+c

In code:

printAll(char[] c, int n, String start){
  if(start.length >= n){
    System.out.println(start)
  }else{
    for(char x in c){ // not a valid syntax in Java
      printAll(c, n, start+x);
    }
  }
}