Übung Parallelisierung ist nur im Hauptordner

Übung4/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.20)
+
+project(prog3b_652)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+add_executable(prog3b main.cpp)

Übung4/main.cpp

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+#include <iostream>
+#include <fstream>
+#include <vector>
+#include <thread>
+#include <chrono>
+#include <cstdlib>
+
+// =====================
+// Datei einlesen
+// =====================
+void readFile(const std::string& filename, std::vector<int>& data)
+{
+    std::ifstream file(filename);
+    int value;
+    while (file >> value)
+        data.push_back(value);
+}
+
+// =====================
+// Serielle Auswertung
+// =====================
+int countSerial(const std::vector<int>& messungen)
+{
+    if (messungen.size() < 2)
+        return 0;
+
+    int increases = 0;
+    for (size_t i = 1; i < messungen.size(); ++i)
+        if (messungen[i] > messungen[i - 1])
+            ++increases;
+
+    return increases;
+}
+
+// =====================
+// Parallele Auswertung
+// =====================
+int countParallel(const std::vector<int>& messungen, int numThreads)
+{
+    if (messungen.size() < 2)
+        return 0;
+
+    int totalComparisons = messungen.size() - 1;
+    if (numThreads > totalComparisons)
+        numThreads = totalComparisons;
+
+    std::vector<int> results(numThreads, 0);
+    std::vector<std::thread> threads;
+
+    int base = totalComparisons / numThreads;
+    int remainder = totalComparisons % numThreads;
+
+    int idx = 1;
+
+    for (int t = 0; t < numThreads; ++t)
+    {
+        int startIdx = idx;
+        int count = base + (t < remainder ? 1 : 0);
+        int endIdx = idx + count - 1;
+        idx = endIdx + 1;
+
+        threads.emplace_back([&, t, startIdx, endIdx]()
+        {
+            int localCount = 0;
+            for (int i = startIdx; i <= endIdx; ++i)
+                if (messungen[i] > messungen[i - 1])
+                    ++localCount;
+
+            results[t] = localCount;
+        });
+    }
+
+    for (auto& th : threads)
+        th.join();
+
+    int total = 0;
+    for (int r : results)
+        total += r;
+
+    return total;
+}
+
+// =====================
+// main
+// =====================
+int main()
+{
+    std::vector<int> messungen;
+
+    // ===== Variante A: Datei =====
+    readFile("measurements.txt", messungen);
+
+    // ===== Variante B: künstliche Daten (statt Datei) =====
+    /*
+    int value = 0;
+    for (size_t i = 0; i < 100000000; ++i)
+        messungen.push_back(value += (rand() % 3 - 1));
+    */
+
+    // ===== Seriell =====
+    auto start = std::chrono::steady_clock::now();
+    int serialResult = countSerial(messungen);
+    auto end = std::chrono::steady_clock::now();
+
+    std::chrono::duration<double> serialTime = end - start;
+    std::cout << "Seriell:  " << serialResult
+              << " | Took: " << serialTime.count() << " s\n";
+
+    // ===== Parallel =====
+    int numThreads = std::thread::hardware_concurrency();
+    if (numThreads == 0) numThreads = 4;
+
+    start = std::chrono::steady_clock::now();
+    int parallelResult = countParallel(messungen, numThreads);
+    end = std::chrono::steady_clock::now();
+
+    std::chrono::duration<double> parallelTime = end - start;
+    std::cout << "Parallel: " << parallelResult
+              << " | Took: " << parallelTime.count() << " s\n";
+
+    return 0;
+}