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Grokking the Coding Interview Patterns in Python

Find All Possible Recipes from Given Supplies

Explore how to apply topological sort to identify all recipes you can create from given supplies and ingredient dependencies. Understand how to manage recipe interdependencies, detect cycles, and efficiently solve this problem in coding interviews.

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Statement

You are given information about nn different recipes. Each recipe is listed in the array recipes, and its corresponding ingredients are provided in the 2D array ingredients. The ithi^{th} recipe, recipes[i], can be prepared if all the necessary ingredients listed in ingredients[i] are available. Some ingredients might need to be created from other recipes, meaning ingredients[i] may contain strings that are also in recipes.

Additionally, you have a string array supplies that contains all the ingredients you initially have, and you have an infinite supply of each.

Return a list of all the recipes you can create. The answer can be returned in any order.

Note: It is possible for two recipes to list each other as ingredients. However, if these are the only two recipes provided, the expected output is an empty list.

Constraints:

  • n ==== recipes.length ==== ingredients.length

  • 1≤1 \leq n ≤100\leq 100

  • 1≤1 \leq ingredients[i].length, supplies.length ≤100\leq 100

  • 1≤1 \leq recipes[i].length, ingredients[i][j].length, supplies[k].length ≤10\leq 10

  • recipes[i], ingredients[i][j], and supplies[k] consist only of lowercase English letters.

  • All the combined values of recipes and supplies are unique.

  • Each ingredients[i] doesn’t contain any duplicate values.

Examples

Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

Find All Possible Recipes from Given Supplies

1.

What is the output if the following lists are given as input?

recipes = [“soup”, “spaghetti”]

ingredients = [[“meat”, “yogurt”, “sauce”], [“pasta”, “salt”, “sauce”]]

supplies = [“meat”, “pasta”, “yogurt”, “sauce”]

A.

[“soup”, “spaghetti”]

B.

[“spaghetti”]

C.

[“soup”]

D.

[]

1 / 4

Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Note: As an additional challenge, we have intentionally hidden the solution to this puzzle.

Sequence - Vertical
Drag and drop the cards to rearrange them in the correct sequence.
1
2
3
4

Try it yourself

Implement your solution in the following coding playground.

We have left the solution to this challenge as an exercise for you. The optimal solution to this problem runs in O(V + E) time and takes O(V + E) space. You may try to translate the logic of the solved puzzle into a coded solution.

Python
usercode > recipe_finder.py
def find_recipes(recipes, ingredients, supplies):
    
    # Replace this placeholder return statement with your code
    return []
Find All Possible Recipes from Given Supplies