Update ShellSortExample.swift

Fix bug. Origin code probally get wrong answer.My fault.

Author: Moon1102

Shell Sort/ShellSortExample.swift

@@ -8,24 +8,25 @@
 
 import Foundation
 
-public func shellSort(_ list: inout [Int]) {
-    
+public func shellSort(_ list : inout [Int])
+{
     var sublistCount = list.count / 2
-   
-    while sublistCount > 0 {
-        
-        for index in 0..<list.count {
-           
-            guard index + sublistCount < list.count else { break }
+    
+    while sublistCount > 0
+    {
+        for var index in 0..<arr.count{
+            
+            guard index + sublistCount < arr.count else { break }
 
-            if list[index] > list[index + sublistCount] {
-                swap(&list[index], &list[index + sublistCount])
+            if arr[index] > arr[index + sublistCount]{
+                swap(&arr[index], &arr[index + sublistCount])
             }
 
             guard sublistCount == 1 && index > 0 else { continue }
-            
-            if list[index - 1] > list[index] {
-                swap(&list[index - 1], &list[index])
+
+            while arr[index - 1] > arr[index] && index - 1 > 0  {
+                swap(&arr[index - 1], &arr[index])
+                index -= 1
             }
         }
         sublistCount = sublistCount / 2