public static ArrayList<String> getPerms(String s) {
// this was just to check that a new List is created with each call
ListWithName<String> permutations = new ListWithName<String>("name-" + new Random().nextInt());
if (s == null) { // error case
return null;
} else if (s.length() == 0) { // base case
permutations.add("");
return permutations;
}
char first = s.charAt(0); // get the first character
String remainder = s.substring(1); // remove the first character
ArrayList<String> words = getPerms(remainder);
for (String word : words) {
for (int j = 0; j <= word.length(); j++) {
String st = insertCharAt(word, first, j);
System.out.println(st + "->" + permutations.name);
permutations.add(st);
}
}
return permutations;
}
static ArrayList<String> perm(String input) {
ListWithName<String> permutations = new ListWithName<String>("name-" + new Random().nextInt());
if (input == null) return null;
else if (input.length() == 0) {
permutations.add("");
return permutations;
}
char ch = input.charAt(0);
ArrayList<String> remPerms = perm(input.substring(1));
for (String w : remPerms) {
for (int i = 0; i < w.length(); i++) {
String left = w.substring(0, i);
String right = w.substring(i);
String comb = left + ch + right;
permutations.add(comb);
}
}
return permutations;
}
