sheet 5 not tested

sheet5/3/main.cpp

@@ -0,0 +1,77 @@
+#include <iostream>
+#include "mayer_primes.h"
+#include <vector>
+#include <algorithm>
+#include "timing.h"
+#include "omp.h"
+using namespace std;
+
+
+
+vector<unsigned int> count_goldbach(unsigned int n)
+{
+    vector<unsigned int> primes = get_primes(n);
+    size_t npr = primes.size();
+    int nthreads = omp_get_max_threads();
+
+    vector<vector<unsigned int>> local_counts(nthreads, vector<unsigned int>(n+1, 0));
+
+    #pragma omp parallel
+    {
+        int tid = omp_get_thread_num();
+        auto &lc = local_counts[tid];
+
+    #pragma omp for schedule(static)
+        for (int j = 0; j < (int)npr; ++j)
+        {
+            unsigned int p = primes[j];
+            for (unsigned int i = j;i < primes.size() && p + primes[i] <= n; ++i)
+            {
+                unsigned int q = primes[i];
+                unsigned int s = p + q;
+
+               lc[s] +=1;
+            }
+        }
+    }
+
+    // combine
+    vector<unsigned int> counts(n+1, 0);
+    for (int t = 0; t < nthreads; ++t)
+        for (unsigned int k = 0; k <= n; ++k)
+            counts[k] += local_counts[t][k];
+
+    return counts;
+}
+
+
+
+
+int main()
+{   
+
+    
+
+    //3
+    vector<unsigned int> counts = count_goldbach(100000);
+    cout << (max_element(counts.begin(), counts.end()) - counts.begin()) << endl; 
+
+    //4
+    vector<unsigned int> nvalues = {10000, 100000, 400000, 1000000, 2000000};
+    double time;
+    unsigned int n;
+    for(unsigned int i = 0; i< nvalues.size(); i++)
+    {
+        n = nvalues.at(i);
+        tic();
+        count_goldbach(n);
+        time = toc();
+        cout << "Time for n=" << n << ": " << time << endl;
+    }
+ 
+
+
+
+
+    return 0;
+}