Pizza toppings cost analysis

# Table: Toppings
# 
# +--------------+---------+
# | Column Name  | Type    |
# +--------------+---------+
# | topping_name | varchar |
# | cost         | decimal |
# +--------------+---------+
# topping_name is the primary key for this table.
# Each row of this table contains topping name and the cost of the topping.
# 
# Write a solution to calculate the total cost of all possible 3-topping pizza combinations from a given list of toppings. The total cost of toppings must be rounded to 2 decimal places.
# 
# Note:
# 
# Do not include the pizzas where a topping is repeated. For example, ‘Pepperoni, Pepperoni, Onion Pizza’.
# 
# Toppings must be listed in alphabetical order. For example, 'Chicken, Onions, Sausage'. 'Onion, Sausage, Chicken' is not acceptable.
# 
# Return the result table ordered by total cost in descending order and combination of toppings in ascending order.
# 
# The result format is in the following example.
#
# Example 1:
# Input:
# Toppings table:
# +--------------+------+
# | topping_name | cost |
# +--------------+------+
# | Pepperoni    | 0.50 |
# | Sausage      | 0.70 |
# | Chicken      | 0.55 |
# | Extra Cheese | 0.40 |
# +--------------+------+
# Output:
# +--------------------------------+------------+
# | pizza                          | total_cost |
# +--------------------------------+------------+
# | Chicken,Pepperoni,Sausage      | 1.75       |
# | Chicken,Extra Cheese,Sausage   | 1.65       |
# | Extra Cheese,Pepperoni,Sausage | 1.60       |
# | Chicken,Extra Cheese,Pepperoni | 1.45       |
# +--------------------------------+------------+
# Explanation:
# There are only four different combinations possible with the three topings:
# - Chicken, Pepperoni, Sausage: Total cost is $1.75 (Chicken $0.55, Pepperoni $0.50, Sausage $0.70).
# - Chicken, Extra Cheese, Sausage: Total cost is $1.65 (Chicken $0.55, Extra Cheese $0.40, Sausage $0.70).
# - Extra Cheese, Pepperoni, Sausage: Total cost is $1.60 (Extra Cheese $0.40, Pepperoni $0.50, Sausage $0.70).
# - Chicken, Extra Cheese, Pepperoni: Total cost is $1.45 (Chicken $0.55, Extra Cheese $0.40, Pepperoni $0.50).
# Output table is ordered by the total cost in descending order.

import pandas as pd

def cost_analysis(toppings: pd.DataFrame) -> pd.DataFrame:
  from itertools import combinations
  toppings = toppings.sort_values('topping_name')
  names = toppings['topping_name'].tolist()
  costs = toppings.set_index('topping_name')['cost']
  rows = []
  for combo in combinations(names, 3):
    pizza = ','.join(combo)
    total_cost = round(sum(costs[t] for t in combo), 2)
    rows.append({'pizza': pizza, 'total_cost': total_cost})
  result = pd.DataFrame(rows)
  result = result.sort_values(['total_cost', 'pizza'], ascending=[False, True]).reset_index(drop=True)
  return result