longestPalindrome.cpp

  int longestPalindrome(string s) {
        map<char, int> count;
        for (char c: s){
            count[c]++;
        }
        int ans = 0;
        for (auto v: count) {
            ans += v.second / 2 * 2;
            if (ans % 2 == 0 && v.second % 2 == 1)
                ans++;
        }
        return ans;
    }