Implement a quickerSort method

app/src/main/java/ch/nuth/zhaw/exbox/SortServer.java

@@ -79,11 +79,36 @@ public class SortServer implements CommandExecutor {
 
     private void quickerSort(int[] arr, int left, int right) {
         // To do Aufgabe 12.1
+        if (right - left < insertion_threshold) {
+            insertionSort(arr, left, right);
+        } else {
+            int l = partition(arr, left, right);
+            quickerSort(arr, left, l - 1);
+            quickerSort(arr, l, right);
+        }
     }
 
     private int partition (int[] arr, int left, int right) {
         // To do Aufgabe 12.1
-        return 0;
+        int pivot = arr[(left + right) / 2];
+
+        while (left <= right) {
+            while (arr[left] < pivot) {
+                left++;
+            }
+
+            while (arr[right] > pivot) {
+                right--;
+            }
+
+            if (left <= right) {
+                swap(arr, left, right);
+                left++;
+                right--;
+            }
+        }
+
+        return left;
     }
 
     private boolean isSorted(int[] a) {