Create apply-discount-every-n-orders.py

Author: kamyu104

Python/apply-discount-every-n-orders.py

@@ -0,0 +1,29 @@
+# Time:  ctor:    O(m), m is the number of all products
+#        getBill: O(p), p is the number of products to bill
+# Space: O(m)
+
+class Cashier(object):
+
+    def __init__(self, n, discount, products, prices):
+        """
+        :type n: int
+        :type discount: int
+        :type products: List[int]
+        :type prices: List[int]
+        """
+        self.__n = n
+        self.__discount = discount
+        self.__curr = 0
+        self.__lookup = {p : prices[i] for i, p in enumerate(products)}
+
+    def getBill(self, product, amount):
+        """
+        :type product: List[int]
+        :type amount: List[int]
+        :rtype: float
+        """
+        self.__curr = (self.__curr+1) % self.__n
+        result = 0.0
+        for i, p in enumerate(product):
+            result += self.__lookup[p]*amount[i]
+        return result * (1.0 - self.__discount/100.0 if self.__curr == 0 else 1.0)