Merge pull request TheAlgorithms#27 from AlvinPH/bubble_sort_MD1

 better bubble sort

Author: dynamitechetan

sorts/bubble_sort.py

@@ -30,8 +30,8 @@ def bubble_sort(collection):
     [-45, -5, -2]
     """
     length = len(collection)
-    for i in range(length-1):
-        for j in range(length-1):
+    for i in range(length-1, -1, -1):#range(length-1, -1, -1)
+        for j in range(i):#range(1, i)
             if collection[j] > collection[j+1]:
                 collection[j], collection[j+1] = collection[j+1], collection[j]