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  1. Sparse Arrays
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Sparse Arrays

  • emailthegyro
     + 0 comments

    A O(strings+queries) solution in C++ using unordered_map where all operations used below are at O(1) according to to implementation document.

    vector<int> matchingStrings(vector<string> strings, vector<string> queries) {
    unordered_map<string, int> frequency;
    vector<int>results;
    
    //counts all occurances of str in strings and populates the frequency map
    for(string str: strings)
        frequency[str]++;
    //writes out the queries occurances in result
    for(string str: queries)
        results.push_back(frequency[str]);
    
     return results;
}