Merge pull request kodecocodes#416 from Moon1102/master

update ShellSortExample.swift

Author: kelvinlauKL

Shell Sort/ShellSortExample.swift

@@ -8,14 +8,12 @@
 
 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 {
-           
+        for var index in 0..<list.count {
+            
             guard index + sublistCount < list.count else { break }
 
             if list[index] > list[index + sublistCount] {
@@ -24,8 +22,9 @@ public func shellSort(_ list: inout [Int]) {
 
             guard sublistCount == 1 && index > 0 else { continue }
 
-            if list[index - 1] > list[index] {
+            while list[index - 1] > list[index] && index - 1 > 0  {
                 swap(&list[index - 1], &list[index])
+                index -= 1
             }
         }
         sublistCount = sublistCount / 2