Generalized Abbreviation

 1 public class Solution {
 2     public List<String> generateAbbreviations(String word) {
 3         List<String> result = new ArrayList<>();
 4 
 5         getAbb(word, 0, 0, "", result);
 6         return result;
 7     }
 8     
 9     private void getAbb(String word, int index, int count, String str, List<String> result) {
10         if (index == word.length()) {
11             if (count > 0) {
12                 str += count;
13             }
14             result.add(str);
15             return;
16         }
17         
18         getAbb(word, index + 1, count + 1, str, result);
19         getAbb(word, index + 1, 0, str + (count > 0 ? count : "") + word.charAt(index), result);
20     }
21 }