How do you solve Method Chaining on LeetCode?

Method Chaining (LeetCode #2891) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n log n) time complexity and O(n) space complexity. Key insight: Method chaining simplifies code and improves readability.

What is the brute force solution for Method Chaining?

The brute force approach for Method Chaining is Brute Force, with O(n²) time complexity and O(1) space complexity. In the brute force approach, we will iterate through each animal in the DataFrame, check if its weight is greater than 100 kilograms, and collect the names of those that meet the criteria. This is straightforward but not efficient. The optimal Optimal Solution approach improves this to O(n log n).

What are the interview tips for Method Chaining?

Practice writing concise code using method chaining. Understand the underlying data structures used in Pandas. Be prepared to explain your thought process clearly.

What are common mistakes when solving Method Chaining?

Not using method chaining effectively, leading to verbose code. Forgetting to sort the results after filtering.

#2891

Method Chaining

Easy

DataFrame operationsMethod chainingFiltering and sorting

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Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(n log n)
Space	O(1)	O(n)

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Intuition

Time O(n log n)Space O(n)

Using method chaining in Pandas allows us to perform filtering and sorting in a single line of code. This is efficient and leverages the power of Pandas to handle data operations seamlessly.

⚙️

Algorithm

3 steps

1Step 1: Use the DataFrame's filter method to select rows where weight > 100.
2Step 2: Use the sort_values method to sort the filtered DataFrame by weight in descending order.
3Step 3: Use the loc method to select only the 'name' column from the sorted DataFrame.

solution.py11 lines

1import pandas as pd
2
3animals = pd.DataFrame({
4    'name': ['Tatiana', 'Khaled', 'Alex', 'Jonathan', 'Stefan', 'Tommy'],
5    'species': ['Snake', 'Giraffe', 'Leopard', 'Monkey', 'Bear', 'Panda'],
6    'age': [98, 50, 6, 45, 100, 26],
7    'weight': [464, 41, 328, 463, 50, 349]
8})
9
10result = animals[animals['weight'] > 100].sort_values(by='weight', ascending=False)['name'].tolist()
11print(result)

ℹ

Complexity note: The time complexity is O(n log n) due to the sorting step, while the space complexity is O(n) because we create a new list to store the results.

1Method chaining simplifies code and improves readability.
2Filtering and sorting can be done efficiently in one line.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.