Commented

Uebung 1/mergeSort_commented.cpp

@@ -0,0 +1,57 @@
+#include "mergeSort.h"
+
+void merge(int array[], int left, int middle, int right) {
+  // Keine verschachtelten Schleifen, jedoch wird jedes Element einmal
+  // bearbeitet -> O(n)
+  int n1 = middle - left + 1;
+  int n2 = right - middle;
+
+  int leftArray[n1];
+  int rightArray[n1];
+
+  for (int i = 0; i < n1; i++) {
+    leftArray[i] = array[left + i];
+  }
+  for (int j = 0; j < n2; j++) {
+    rightArray[j] = array[middle + j + 1];
+  }
+
+  int k = 0, l = 0, m = left;
+  while (k < n1 && l < n2) {
+    if (leftArray[k] <= rightArray[l]) {
+      array[m] = leftArray[k];
+      k++;
+    } else {
+      array[m] = rightArray[l];
+      l++;
+    }
+    m++;
+  }
+
+  while (k < n1) {
+    array[m] = leftArray[k];
+    k++;
+    m++;
+  }
+
+  while (l < n2) {
+    array[m] = rightArray[l];
+    l++;
+    m++;
+  }
+}
+
+void mergeSort(int array[], int left, int right) {
+  if (left < right) {
+    int middle = left + (right - left) / 2;
+
+    // O(T(n/2))
+    mergeSort(array, left, middle);
+    // O(T(n/2))
+    mergeSort(array, middle + 1, right);
+    // O(n)
+    merge(array, left, middle, right);
+  }
+}
+//
+// Insgesamt: 2 * O(T(n/2)) + O(n) -> Master Theorem -> O(n log n)