Update 5.mergeSort.md

Author: JerryChii

5.mergeSort.md

@@ -76,24 +76,23 @@ function merge(left, right)
 
 ```python
 def mergeSort(arr):
-    import math
     if(len(arr)<2):
         return arr
-    middle = math.floor(len(arr)/2)
+    middle = len(arr)/2
     left, right = arr[0:middle], arr[middle:]
     return merge(mergeSort(left), mergeSort(right))
 
 def merge(left,right):
     result = []
     while left and right:
         if left[0] <= right[0]:
-            result.append(left.pop(0));
+            result.append(left.pop(0))
         else:
-            result.append(right.pop(0));
+            result.append(right.pop(0))
     while left:
-        result.append(left.pop(0));
+        result.extend(left)
     while right:
-        result.append(right.pop(0));
+        result.extend(right)
     return result
 ```