Amazon VO 面试真题解析：Build a Furniture Store Order Pricing System 订单定价系统

Build a system that calculates the price of a customer’s order in a furniture store. Pricing rules are as follows:

• Used items get a 20% discount off the original price.
• Buying multiple items of the same category (e.g., chairs) applies an additional discount:
• 2-3 items: 5% off
• 4-6 items: 10% off
• 7+ items: 15% off
• There is a category-based pricing tier for each item similar to the following:

CATEGORY_PRICES = {'chair': {'basic': 100, 'premium': 200, 'luxury': 300},
    'table': {'basic': 250, 'premium': 500, 'luxury': 1000},
    'sofa': {'basic': 500, 'premium': 1000, 'luxury': 2000},
    'cabinet': {'basic': 300, 'premium': 600, 'luxury': 900}
}

Example usage:

items = [{'name': 'Classic Chair', 'category': 'chair', 'tier': 'basic', 'used': True},
    {'name': 'Designer Chair', 'category': 'chair', 'tier': 'premium', 'used': False},
    {'name': 'Luxury Table', 'category': 'table', 'tier': 'luxury', 'used': False}
]

Expected output:

• Basic Chair: 100 * 0.8 = 80 (used discount)
• Premium Chair: 200 (no used discount)
• Both chairs get 5% category discount

这道题考察的是订单计价规则的建模与批量折扣计算。做题时需要先根据商品的 category 和 tier 从价格表中取出基础价格，再对 used 商品先打 8 折；随后按同类商品数量应用阶梯式 category 折扣：2-3 件 95 折、4-6 件 9 折、7 件及以上 85 折。实现上通常会先按 category 分组，统计每组数量，再统一计算每个商品的最终价格，避免重复扣减或漏算折扣。