Unique Word Abbreviation

An abbreviation of a word follows the form . Below are some examples of word abbreviations:

  1. a) it                      --> it    (no abbreviation)
  3.      1
  4. b) d|o|g                   --> d1g
  6.               1    1  1
  7.      1---5----0----5--8
  8. c) i|nternationalizatio|n  --> i18n
  10.               1
  11.      1---5----0
  12. d) l|ocalizatio|n          --> l10n

Assume you have a dictionary and given a word, find whether its abbreviation is unique in the dictionary. A word’s abbreviation is unique if no other word from the dictionary has the same abbreviation.

Example:

  1. Given dictionary = [ "deer", "door", "cake", "card" ]
  3. isUnique("dear") -> false
  4. isUnique("cart") -> true
  5. isUnique("cane") -> false
  6. isUnique("make") -> true

Solution:

  1. public class ValidWordAbbr {
  2.   Map<String, Set<String>> map = new HashMap<>();
  4.   public ValidWordAbbr(String[] dictionary) {
  5.     // build the hashmap
  6.     // the key is the abbreviation
  7.     // the value is a hash set of the words that have the same abbreviation
  8.     for (int i = 0; i < dictionary.length; i++) {
  9.       String a = abbr(dictionary[i]);
  10.       Set<String> set = map.containsKey(a) ? map.get(a) : new HashSet<>();
  11.       set.add(dictionary[i]);
  12.       map.put(a, set);
  13.     }
  14.   }
  16.   public boolean isUnique(String word) {
  17.     String a = abbr(word);
  18.     // it's unique when the abbreviation does not exist in the map or
  19.     // it's the only word in the set
  20.     return !map.containsKey(a) || (map.get(a).contains(word) && map.get(a).size() == 1);
  21.   }
  23.   String abbr(String s) {
  24.     if (s.length() < 3) 
  25.       return s;
  27.     return s.substring(0, 1) + String.valueOf(s.length() - 2) + s.substring(s.length() - 1);
  28.   }
  29. }
  32. // Your ValidWordAbbr object will be instantiated and called as such:
  33. // ValidWordAbbr vwa = new ValidWordAbbr(dictionary);
  34. // vwa.isUnique("Word");
  35. // vwa.isUnique("anotherWord");