Apply Discount Every n Orders — LeetCode 1357 Python Solution

The problem

There is a supermarket that is frequented by many customers. The products sold at the supermarket are represented as two parallel integer arrays products and prices, where the ith product has an ID of products[i] and a price of prices[i].

Example

Input

["Cashier","getBill","getBill","getBill","getBill","getBill","getBill","getBill"]

Output

[null,500.0,4000.0,800.0,4000.0,4000.0,7350.0,2500.0]

Explanation

Cashier cashier = new Cashier(3,50,[1,2,3,4,5,6,7],[100,200,300,400,300,200,100]);

Python solution

class Cashier:
    def __init__(self, n: int, discount: int, products: List[int], prices: List[int]):
        self.i = 0
        self.n = n
        self.discount = discount
        self.d = {product: price for product, price in zip(products, prices)}

    def getBill(self, product: List[int], amount: List[int]) -> float:
        self.i += 1
        discount = self.discount if self.i % self.n == 0 else 0
        ans = 0
        for p, a in zip(product, amount):
            x = self.d[p] * a
            ans += x - (discount * x) / 100
        return ans


# Your Cashier object will be instantiated and called as such:
# obj = Cashier(n, discount, products, prices)
# param_1 = obj.getBill(product,amount)

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 1357. Apply Discount Every n Orders is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Hash Table.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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