LeetCode 256. Unique Word Abbreviation

#include <string>
#include <vector>
#include <unordered_set>
#include <iostream>
using namespace std;

/*
    An abbreviation of a word follows the form <first letter><number><last letter>
    Below are some example of word abbreviations.
    1: it  -> it
    2: dog -> d1g
    3: internationalization -> i18n
*/

// just use an unordered_set is enough.....

class ValidWordAbbr{

private:
    unordered_set<string> map;

public:
    ValidWordAbbr(vector<string>& dictionary) {
        for(int i = 0; i < dictionary.size(); ++i) {
            int n = dictionary[i].size();
            if(n <= 2) map.emplace(dictionary[i]);
            else {
                string tmp = dictionary[i][0] + to_string(n - 2) + dictionary[i][n-1];
                map.emplace(tmp);
            }
        }
    }

    bool isUnique(string word) {
        int n = word.size();
        if(n > 2) {
            string tmp = word[0] + to_string(n-2) + word[n-1];
        } else tmp = word;

        if(map.find(tmp) == map.end()) return true;
        else return false;
    }
};

int main(void) {
    vector<string> dictionary{"deer", "door", "cake", "card"};
    ValidWordAbbr strMap(dictionary);
    cout << strMap.isUnique("datr") << endl;
}