Update campus-bikes-ii.py

Author: kamyu104

Python/campus-bikes-ii.py

@@ -1,6 +1,8 @@
 # Time:  O(w * b * 2^b)
 # Space: O(b * 2^b)
 
+# if w = b, we can even apply Hungarian algorithm (see https://en.wikipedia.org/wiki/Hungarian_algorithm),
+# it can be improved to O(w^3), see https://github.com/t3nsor/codebook/blob/master/bipartite-mincost.cpp
 class Solution(object):  # this is slower than Solution2 in python
     def assignBikes(self, workers, bikes):
         """