Update Shellsort List.md

Grade 10/Computer Science/ICS4U1/Sorting Methods/Shellsort List.md

@@ -1,6 +1,7 @@
 # Shell Sort Handout
 
 ## What is shell sort?
+- "Diminishing Increment Sort", better known as comb sort
 - Combination of sorting by insertion (insertion sort) and sorting by exchange (bubble sort)
 - Starts off by comparing two elements that are far apart and gradually reduce the gap between them
 - It works better than regular insertion sort as it moves certain out of place elements into place faster
@@ -44,4 +45,12 @@ public static void shellSort(int arr[]) // Method Header
         }
     }
     
-```
+```
+
+## Enhanced Shell Sort
+- A method to calculate the gap sequence and can decrease the number of comparisons by up to 60%
+- Published by Basit Shahzad and Muhammad Tanvir Afzal from the World Academy of Science
+- The gap sequence would be h<sub>1</sub> and h<sub>n+1</sub> = 3h<sub>n</sub>+1
+- For 100 elements, shell's original gap seuqence will make 170 comparisons but the Enhanced Shell Sort will make 85 comparisons
+
+