Calculate product final price

# Table: Products
# 
# +------------+---------+
# | Column Name| Type    |
# +------------+---------+
# | product_id | int     |
# | category   | varchar |
# | price      | decimal |
# +------------+---------+
# product_id is the unique key for this table.
# Each row includes the product's ID, its category, and its price.
# 
# Table: Discounts
# 
# +------------+---------+
# | Column Name| Type    |
# +------------+---------+
# | category   | varchar |
# | discount   | int     |
# +------------+---------+
# category is the primary key for this table.
# Each row contains a product category and the percentage discount applied to that category (values range from 0 to 100).
# 
# Write a solution to find the final price of each product after applying the category discount. If a product's category has no associated discount, its price remains unchanged.
# 
# Return the result table ordered by product_id in ascending order.
# 
# The result format is in the following example.
#
# Example 1:
# Input:
# Products table:
# +------------+-------------+-------+
# | product_id | category    | price |
# +------------+-------------+-------+
# | 1          | Electronics | 1000  |
# | 2          | Clothing    | 50    |
# | 3          | Electronics | 1200  |
# | 4          | Home        | 500   |
# +------------+-------------+-------+
# Discounts table:
# +------------+----------+
# | category   | discount |
# +------------+----------+
# | Electronics| 10       |
# | Clothing   | 20       |
# +------------+----------+
# Output:
# +------------+------------+-------------+
# | product_id | final_price| category    |
# +------------+------------+-------------+
# | 1          | 900        | Electronics |
# | 2          | 40         | Clothing    |
# | 3          | 1080       | Electronics |
# | 4          | 500        | Home        |
# +------------+------------+-------------+
# Explanation:
# For product 1, it belongs to the Electronics category which has a 10% discount, so the final price is 1000 - (10% of 1000) = 900.
# For product 2, it belongs to the Clothing category which has a 20% discount, so the final price is 50 - (20% of 50) = 40.
# For product 3, it belongs to the Electronics category and receives a 10% discount, so the final price is 1200 - (10% of 1200) = 1080.
# For product 4, no discount is available for the Home category, so the final price remains 500.
# Result table is ordered by product_id in ascending order.

import pandas as pd

def calculate_final_prices(products: pd.DataFrame, discounts: pd.DataFrame) -> pd.DataFrame:
  merged = products.merge(discounts, on='category', how='left')
  merged['discount'] = merged['discount'].fillna(0)
  merged['final_price'] = (merged['price'] * (1 - merged['discount'] / 100)).round(2)
  return merged[['product_id', 'final_price', 'category']].sort_values('product_id')