lesson_2/Timer.hpp

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+/*
+ * Timer.hpp
+ *
+ *  Created on: 26 сент. 2021 г.
+ *      Author: alexander
+ */
+
+#pragma once
+
+#include <iostream>
+#include <chrono>
+
+class Timer
+{
+private:
+    using clock_t = std::chrono::high_resolution_clock;
+    using second_t = std::chrono::duration<double, std::ratio<1> >;
+
+    std::string m_name;
+    std::chrono::time_point<clock_t> m_beg;
+    double elapsed() const
+    {
+        return std::chrono::duration_cast<second_t>(clock_t::now() -m_beg).count();
+    }
+
+public:
+    Timer() : m_beg(clock_t::now()) { }
+    Timer(std::string name) : m_name(name), m_beg(clock_t::now()) { }
+
+    void start(std::string name) {
+        m_name = name;
+        m_beg = clock_t::now();
+    }
+    void print() const {
+        std::cout << m_name << ":\t" << elapsed() * 1000 << " ms" << '\n';
+    }
+};

lesson_2/main.cpp

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+/*
+ * main.cpp
+ *
+ *  Created on: 26 сент. 2021 г.
+ *      Author: alexander
+ */
+#include <iostream>
+#include <fstream>
+#include <vector>
+#include <algorithm>
+#include "Timer.hpp"
+
+using namespace std;
+
+template<typename T>
+void Swap(T *a, T *b)
+{
+    T temp = *a;
+    *a = *b;
+    *b = temp;
+}
+
+template<typename T>
+void SortPointers(vector<T*> &v)
+{
+    sort(v.begin(), v.end(), [](const auto &v1, const auto &v2)
+    {
+        return *v1 < *v2;
+    });
+}
+
+void exercise_1()
+{
+    int a(5);
+    int b(6);
+
+    Swap(&a, &b);
+
+    cout << a << ' ' << b << endl;
+}
+
+void exercise_2()
+{
+    int length = 5;
+    vector<int*> v;
+
+    for (int i = 0; i < length; ++i)
+    {
+        int *a = new int;
+        *a = rand() % 10;
+        v.push_back(a);
+    }
+
+    for (int i = 0; i < length; ++i)
+    {
+        cout << *v[i] << ' ';
+    }
+
+    cout << endl;
+
+    SortPointers(v);
+
+    for (int i = 0; i < length; ++i)
+    {
+        cout << *v[i] << ' ';
+    }
+
+    cout << endl;
+}
+
+namespace counting
+{
+    const string_view vowels
+    { "AEIOUaeiou" };
+
+    void way1(const string_view &s)
+    {
+        Timer timer("Counting vowels [way 1]");
+        size_t count = count_if(s.begin(), s.end(), [&](const auto &c)
+        {
+            return vowels.find(c) != string::npos;
+        });
+        cout << count << endl;
+        timer.print();
+    }
+
+    void way2(const string_view &s)
+    {
+        Timer timer("Counting vowels [way 2]");
+        size_t count = count_if(s.begin(), s.end(), [&](const auto &c)
+        {
+            for (size_t i = 0; i < vowels.size(); ++i)
+            {
+                if (vowels[i] == c)
+                return true;
+            }
+            return false;
+        });
+        cout << count << endl;
+        timer.print();
+    }
+
+    void way3(const string_view &s)
+    {
+        size_t count = 0;
+        Timer timer("Counting vowels [way 3]");
+        for (size_t i = 0; i < s.size(); ++i)
+        {
+            if (vowels.find(s[i]) != string::npos)
+            {
+                ++count;
+            }
+        }
+        cout << count << endl;
+        timer.print();
+    }
+
+    void way4(const string_view &s)
+    {
+        size_t count = 0;
+        Timer timer("Counting vowels [way 4]");
+        for (size_t i = 0; i < s.size(); ++i)
+        {
+            for (size_t j = 0; j < vowels.size(); ++j)
+            {
+                if (vowels[j] == s[i])
+                    ++count;
+            }
+        }
+        cout << count << endl;
+        timer.print();
+    }
+}
+
+void exercise_3()
+{
+    ifstream file("War_and_peace.txt");
+    file.seekg(0, ios::end);
+    size_t size = file.tellg();
+    file.seekg(0);
+    string s(size, ' ');
+    file.read(&s[0], size);
+
+    counting::way1(s);               // Counting vowels [way 1]:    59.6968 ms
+    counting::way2(s);               // Counting vowels [way 2]:    177.219 ms
+    counting::way3(s);               // Counting vowels [way 3]:    51.9079 ms
+    counting::way4(s);               // Counting vowels [way 4]:    234.762 ms
+}
+
+int main()
+{
+//    exercise_1();
+//    exercise_2();
+    exercise_3();
+
+    return 0;
+}