An abbreviation of a word follows the form <first letter><number><last letter>. Below are some examples of word abbreviations:

a) it                      --> it    (no abbreviation)     1b) d|o|g                   --> d1g              1    1  1     1---5----0----5--8c) i|nternationalizatio|n  --> i18n              1     1---5----0d) 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: 

Given dictionary = [ "deer", "door", "cake", "card" ]isUnique("dear") -> falseisUnique("cart") -> trueisUnique("cane") -> falseisUnique("make") -> true

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解题思路：

解题关键点有3个：

1. 找出word abbreviation 的规律，<first letter><number><last letter>，number = string.length() - 2

2. 当发现dictionary 里有相同的abbreviation, key 对应的value 变为"" 

3. The abbreviation of "hello", i.e., h3o already exists in the dictionary.

Input: ["hello"],isUnique("hello") Output: [false] Expected: [true]

If the given word itself is in the dictionary, and it has the unique abbreviation, then we should return true.

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Java code:

public class ValidWordAbbr {    private Map
     
       map = new HashMap
      
       ();    public ValidWordAbbr(String[] dictionary) {        for(int i = 0; i < dictionary.length; i++){            String key = abbreviate(dictionary[i]);            if(!map.containsKey(key)){                map.put(key, dictionary[i]);            }else{                map.put(key, "");            }        }    }        private String abbreviate(String str){        return str.charAt(0) + Integer.toString(str.length() - 2)+ str.charAt(str.length()-1);    }    public boolean isUnique(String word) {        String x = abbreviate(word);        if(map.containsKey(x)){            if(map.get(x).equals(word)){                return true;            }else {                return false;            }        }        return true;    }}// Your ValidWordAbbr object will be instantiated and called as such:// ValidWordAbbr vwa = new ValidWordAbbr(dictionary);// vwa.isUnique("Word");// vwa.isUnique("anotherWord");
      
     

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Reference:

1. https://leetcode.com/discuss/62842/a-simple-java-solution-using-map-string-string

2. https://leetcode.com/discuss/62824/wrong-test-case