c_cpp 给定一组单词，返回给定集合中的anagrams集合

Posted 2021-05-14

vector<string> get_collection_of_anagrams(const vector<string> &words) {
    vector<string> res;
    if(words.empty()) return res;
    unordered_map<string, vector<int>> hash;
    for(int i=0; i<words.size(); i++) {
        string s = words[i];
        sort(s.begin(), s.end());
        if(hash.find(s) != hash.end()) 
            hash[s].push_back(i);
        else {
            vector<int> v = {i};
            hash[s] = v;
        }
    }
    for(auto p : hash) {
        if(p.second.size() >= 2) {
            for(int i : p.second)
                res.push_back(words[i]);
        }
    }
    return res;
}

// another similar version
vector<string> get_collections_of_anagrams(const vector<string>& words) {
    vector<string> result;
    int n = words.size();
    if(n == 0 || n == 1)
        return result;
    unordered_map<string, vector<string>> hash;
    for(string word : words) {
        string sorted = word;
        sort(sorted.begin(), sorted.end());
        if(hash.find(sorted) == hash.end()) {
            vector<string> vs;
            vs.push_back(word);
            hash[sorted] = vs;
        }
        else { /* consider duplications?
            vector<string> *v = &hash[sorted];
            if(v->find(word) == v->end())
                v->push_back(word); */
        
            hash[sorted].push_back(word);
        }
    }
    for(auto& p : hash) {
        if(p.second.size() >= 2) {
            for(string& s : p.second)
                result.push_back(s);
        }
    }
    return result;
}