Implement a method to merge K sorted arrays.\nThe time complexity must be better than ```O(N*K)```.\nMethod signature (C++): ```vector<char> merge(vector<vector<char>> chunks)```\n\n***\n*(Edit)* Here is an ```O(N log K)``` solution I proposed (the interviewer seemed to be satisfied with it).\nIf anyone has a better idea - please post.\n```\nvector<char> merge(vector<vector<char>>& chunks)\n{\n    typedef pair<vector<char>::iterator, vector<char>::iterator> it_pair;\n    auto comp = [](auto& a, auto& b){return *a.first > *b.first;};\n    priority_queue<it_pair, vector<it_pair>, decltype(comp)> q(comp);\n    for(auto& v : chunks) q.push({v.begin(), v.end()});\n    vector<char> res;\n    while(q.size())\n    {\n        auto [it, end] = q.top(); q.pop();\n        res.push_back(*it);\n        if(++it != end) q.push({it, end});\n    }\n    return res;\n}\n```

Implement a method to merge K sorted arrays.\nThe time complexity must be better than O(N*K).\nMethod signature (C++): vector<char> merge(vector<vector<char>> c