发表于 2024.08.30

• 很简单的哈希表应用题，使用一个哈希表记录商品id和价格的映射关系，然后每次调用getBill计算账单时，累加商品价格，如果当前是第n个顾客，那么就打折。

  C++的做法：

  class Cashier {
  public:
      Cashier(int n, int discount, vector<int>& products, vector<int>& prices) : n(n), discount(discount) {
          for (int i = 0; i < products.size(); ++i) price_map.insert({ products[i], prices[i] });
  
      }
      
      double getBill(vector<int> product, vector<int> amount) {
          double total = 0;
          for (int i = 0; i < product.size(); ++i)
              total += price_map[product[i]] * amount[i];
          if (++processed % n == 0) total = total * ((100 - discount) / 100.0);
          return total;
      }
  private:
      int n;
      int discount;
      int processed {0};
      unordered_map<int, int> price_map;
  };

  Python的做法：

  class Cashier:
  
      def __init__(self, n: int, discount: int, products: List[int], prices: List[int]):
          self._price_map = {product: price for product, price in zip(products, prices)}
          self._n = n
          self._discount = discount
          self._processed = 0
  
      def getBill(self, product: List[int], amount: List[int]) -> float:
          self._processed += 1
          total = sum(self._price_map[product_id] * cnt for product_id, cnt in zip(product, amount))
          if not self._processed % self._n:
              total = total * ((100 - self._discount) / 100)
          return float(total)

• LC 题目链接