https://leetcode.com/problems/longest-palindrome/

Source

    int longestPalindrome(string s) {
        unordered_map<char, int> hashMap;
        for (char c : s) {
            hashMap[c]++;
        }
        int oneside = 0;
        int addOne = 0;
        for (auto it=std::begin(hashMap); std::end(hashMap)!=it; ++it) {
            const char c = it->first;
            const int num = hashMap[c];
            const int half = static_cast<int>(num/2);
            if (half > 0) oneside += half;
            if (num%2 > 0) addOne = 1;
        }
        return (2*oneside + addOne);
    }

GitHub

• LongestPalindrome