speed.cpp

#include <algorithm>
#include <cstdlib>
#include <vector>
#include <ctime>
#include <iostream>

using namespace std;

template <typename T>
void straightSelectionSort2(const T& begin, const T& end)
{
    if (begin == end)
        return;
    for (T i = begin; i != end - 1; ++i)
    {
        T min = i;
        // je je ukazatel na položku, se kterou se porovnává
        for (T j = i + 1; j != end; ++j)
            if (*j < *min)
                min = j;
        if (*min != *i)
            std::iter_swap(min, i);
    }
}

template <typename T>
void straightSelectionSortIndex(T &container, int size)
{
      for (int i = 0; i != size - 1; ++i)
      {
            int min = i;
            for (int j = i + 1; j != size; ++j)
                  if (container[j] < container[min])
                        min = j;
            if (container[min] != container[i])
                  std::swap(container[i], container[min]);
      }
}

template <typename T>
void straightSelectionSort3(const T& begin, const T& end)
{
    if (begin == end)
        return;
    // i je ukazatel na první položku nesetříděné části
    for (T i = begin; i != end - 1; ++i)
    {
        std::iter_swap(i, std::min_element(i, end));
    }
}

int main()
{
    const size_t SIZE = 100000;
    std::vector<int> v;
    v.reserve(SIZE);
    srand(1);
    for (size_t i = 0; i < SIZE; ++i)
        v.push_back(rand());

    clock_t start, stop;

    start = clock();
    straightSelectionSortIndex(v, v.size()); // varianta index
    stop = clock();
    cout << static_cast<float>(stop - start) / CLOCKS_PER_SEC << endl;

    start = clock();
    straightSelectionSort2(v.begin(), v.end());  // varianta sort2
    stop = clock();
    cout << static_cast<float>(stop - start) / CLOCKS_PER_SEC << endl;
    
    start = clock();
    straightSelectionSort3(v.begin(), v.end());  // varianta sort3
    stop = clock();
    cout << static_cast<float>(stop - start) / CLOCKS_PER_SEC << endl;
}