【C++】std::vectorをマージして、ソートと重複削除を行うテスト。

cpp_merge_vector_and_sort_with_erase_duplicates_test.cpp

/**************************************************************************//**
 * @brief   Example of merge std::vector And sort with erase duplicates.
 * @par     Bibliography
 *          http://stackoverflow.com/questions/1041620/most-efficient-way-to-erase-duplicates-and-sort-a-c-vector
 *
 * @author  Mitsu
 * @date    2014-07-07. 七夕！
 ******************************************************************************/
#include <chrono>
#include <iostream>
#include <set>
#include <string>
#include <sstream>
#include <vector>

// for test.
template <class CONTAINER>
std::string dumpContainer(CONTAINER container)
{
    std::stringstream ss;
    for(auto v : container)
        ss << v << ", ";
    return ss.str();
}


// Use for when the number of duplicates is large enough.
void sortAndEraseDuplicates_useSet(std::vector<int>& vec)
{
    // std::set<int> s(vec.begin(), vec.end());    // convert to set.
    // vec.assign(s.begin(), s.end());             // reconvert to vector.

    // faster?
    std::set<int> s;
    unsigned size = vec.size();
    for(unsigned i = 0; i < size; ++i)
        s.insert(vec[i]);
    vec.assign(s.begin(), s.end());
}

// Use for when the number of duplicates is little.
void sortAndEraseDuplicates_useUnique(std::vector<int>& vec)
{
    std::sort(vec.begin(), vec.end());  // sort for unique.
    vec.erase(std::unique(vec.begin(), vec.end()), vec.end());
}

int main(int argc, char **argv)
{
    std::vector<int> vec1 = {0, 1, 2, 3, 4};
    std::vector<int> vec2 = {3, 4, 2, 3, 5};

    std::cout << "vec1: " << dumpContainer(vec1) << std::endl;
    std::cout << "vec2: " << dumpContainer(vec2) << std::endl;
    std::cout << "--------------------" << std::endl;

    //------------------------------
    // Merge!
    vec1.insert(vec1.end(), vec2.begin(), vec2.end());
    std::cout << "vec1 insert vec2: " << dumpContainer(vec1) << std::endl;

    //------------------------------
    // Sort & Erase Duplicates!
    {   // A. Use std::set.
        std::vector<int> test(vec1.begin(), vec1.end());
        sortAndEraseDuplicates_useSet(test);
        std::cout << "Sort&EraseDuplicates(Use std::set): " << dumpContainer(test) << std::endl;
    }
    {   // B. Use std::unique.
        std::vector<int> test(vec1.begin(), vec1.end());
        sortAndEraseDuplicates_useUnique(test);
        std::cout << "Sort&EraseDuplicates(Use std::unique): " << dumpContainer(test) << std::endl;
    }

    return 0;
}