Pizza Toppings Cost Analysis - Practice Coding Problems

Pizza Toppings Cost Analysis - Problem

Database Medium

You are given a table Toppings that contains information about pizza toppings and their costs.

Table: Toppings

Column Name	Type
topping_name	varchar
cost	decimal

topping_name is the primary key for this table. Each row contains a topping name and its cost.

Problem:

Calculate the total cost of all possible 3-topping pizza combinations
Round the total cost to 2 decimal places
Do not include combinations where a topping is repeated
List toppings in alphabetical order within each combination
Order results by total cost descending, then by topping combination ascending

Table Schema

Toppings

Column Name	Type	Description
`topping_name` PK	varchar	Name of the pizza topping (primary key)
`cost`	decimal	Cost of the topping in dollars

Primary Key: topping_name

Note: Each row represents a unique pizza topping with its associated cost

Input & Output

Example 1 — Basic Pizza Combinations

Input Table:

topping_name	cost
Beef	1.2
Chicken	1.3
Cheese	0.9
Pepperoni	1.5

Output:

pizza	total_cost
Chicken,Cheese,Pepperoni	3.7
Beef,Chicken,Pepperoni	4
Beef,Cheese,Pepperoni	3.6
Beef,Chicken,Cheese	3.4

💡 Note:

With 4 toppings, we can create C(4,3) = 4 unique combinations. Each combination lists toppings alphabetically and shows the sum of their costs rounded to 2 decimal places. Results are ordered by total cost descending, then by pizza name ascending.

Example 2 — Minimal Case

Input Table:

topping_name	cost
Cheese	1
Pepperoni	2
Mushroom	1.5

Output:

pizza	total_cost
Cheese,Pepperoni,Mushroom	4.5

💡 Note:

With exactly 3 toppings, there is only one possible combination. The toppings are listed alphabetically (Cheese, Mushroom, Pepperoni becomes Cheese,Pepperoni,Mushroom) with total cost 4.50.

Example 3 — No Valid Combinations

Input Table:

topping_name	cost
Cheese	1
Pepperoni	2

Output:

pizza	total_cost

💡 Note:

With only 2 toppings available, it's impossible to create any 3-topping combinations. The result is an empty set.

Constraints

1 ≤ number of toppings ≤ 1000
topping_name consists of letters and spaces only
0.01 ≤ cost ≤ 100.00
cost has at most 2 decimal places

Visualization

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Understanding the Visualization

Input

Toppings table with names and costs

Self-Join

Triple self-join with ordering constraints

Output

All unique 3-topping combinations with costs

Key Takeaway

🎯 Key Insight: Use self-joins with proper ordering constraints to generate unique combinations systematically

Asked in

A Amazon 28 M Microsoft 22 G Google 19

Use triple self-join with t1.topping_name < t2.topping_name < t3.topping_name constraints to generate unique alphabetically-ordered 3-topping combinations, then calculate and format total costs.

Table Schema

Toppings

Column Name	Type	Description
`topping_name` PK	varchar	Name of the pizza topping (primary key)
`cost`	decimal	Cost of the topping in dollars

Primary Key: topping_name

Note: Each row represents a unique pizza topping with its associated cost

Common Approaches

Approach	Time	Space	Notes
✓ Triple Self-Join	O(n³)	O(n³)	Join the Toppings table with itself three times to create all unique 3-topping combinations

Triple Self-Join — Algorithm Steps

Step 1: Self-join table 3 times with different aliases
Step 2: Apply ordering constraints to ensure alphabetical combinations
Step 3: Calculate sum and round to 2 decimal places
Step 4: Order by cost DESC, combination ASC

Visualization

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Step-by-Step Walkthrough

Self-Join

Join table with itself 3 times

Filter

Apply alphabetical constraints

Calculate

Sum costs and format output

Code -

solution.c — C

Time & Space Complexity

Time Complexity

⏱️

O(n³)

Three nested loops through all toppings

⚠ Quadratic Growth

Space Complexity

O(n³)

Storage for all possible 3-topping combinations

⚠ Quadratic Space

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Smart Actions

💡 Explanation

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Table Schema

Input & Output

Constraints

Visualization

Related Problems

Table Schema

Common Approaches

Triple Self-Join — Algorithm Steps

Visualization

Code -

Time & Space Complexity

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