Merge pull request kodecocodes#392 from Moon1102/master

add file ShellSortExample.swift

Author: kelvinlauKL

Shell Sort/ShellSortExample.swift

@@ -0,0 +1,33 @@
+//
+//  ShellSortExample.swift
+//  
+//
+//  Created by Cheer on 2017/2/26.
+//
+//
+
+import Foundation
+
+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 }
+            
+            if list[index] > list[index + sublistCount] {
+                swap(&list[index], &list[index + sublistCount])
+            }
+            
+            guard sublistCount == 1 && index > 0 else { continue }
+            
+            if list[index - 1] > list[index] {
+                swap(&list[index - 1], &list[index])
+            }
+        }
+        sublistCount = sublistCount / 2
+    }
+}