module6/src/main/java/com/hithomelabs/princeton1/module6/Merge.java

@@ -7,6 +7,34 @@ import java.util.Arrays;
 public class Merge<E> extends AbstractCustomSorts<E> {
     @Override
     public void sort(E[] arr) {
+        merge_sort(arr, 0, arr.length-1);
+    }
+
+    private void merge_sort(E[] arr, int low_index, int high_index){
+        System.out.println(low_index + " " + high_index);
+        if(high_index - low_index > 0) {
+            int mid_index = low_index + (high_index - low_index)/2;
+            merge_sort(arr, low_index, mid_index);
+            merge_sort(arr, mid_index + 1, high_index);
+
+            // Copy array
+            E[] auxArr = (E[]) new Object[arr.length];
+            System.arraycopy(arr, 0, auxArr, 0, arr.length);
+
+            // Sort
+            int low_index_ptr = low_index;
+            int high_index_ptr = mid_index + 1;
+            for(int i=low_index; i<= high_index; i++){
+                if(low_index_ptr > mid_index)
+                    arr[i] = auxArr[high_index_ptr++];
+                else if(high_index_ptr > high_index)
+                    arr[i] = auxArr[low_index_ptr++];
+                else if(less((Comparable<E>) auxArr[low_index_ptr], auxArr[high_index_ptr]))
+                    arr[i] = auxArr[low_index_ptr++];
+                else
+                    arr[i] = auxArr[high_index_ptr++];
+            }
+        }
     }
 }