Update number-of-orders-in-the-backlog.py

Author: kamyu104

Python/number-of-orders-in-the-backlog.py

@@ -1,6 +1,9 @@
 # Time:  O(nlogn)
 # Space: O(n)
 
+import heapq
+
+
 class Solution(object):
     def getNumberOfBacklogOrders(self, orders):
         """