288. Unique Word Abbreviation

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)

     1
     ↓
b) d|o|g                   --> d1g

              1    1  1
     1---5----0----5--8
     ↓   ↓    ↓    ↓  ↓    
c) i|nternationalizatio|n  --> i18n

              1
     1---5----0
     ↓   ↓    ↓
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:

Given dictionary = [ "deer", "door", "cake", "card" ]

isUnique("dear") -> false
isUnique("cart") -> true
isUnique("cane") -> false
isUnique("make") -> true

class ValidWordAbbr {
public:
    ValidWordAbbr(vector<string> dictionary) {
        for (string& str : dictionary) {
            int n = str.size();
            string a = n <= 2 ? str : str[0] + to_string(n - 2) + str[n - 1];
            m[a].insert(str);
        }
    }
    
    bool isUnique(string word) {
        int n = word.size();
        string a = n <= 2 ? word : word[0] + to_string(n - 2) + word[n - 1];
        // if (m.count(a)) {
        //     if (m[a].count(word) && m[a].size() == 1) return true;
        //     else return false;
        // } else {
        //     return true;
        // }
        return (m.count(a) && m[a].count(word) && m[a].size() == 1) || !m.count(a);
    }
    unordered_map<string, unordered_set<string> > m;
};