Leetcode #2891: Method Chaining
In this guide, we solve Leetcode #2891 Method Chaining in Python and focus on the core idea that makes the solution efficient.
You will see the intuition, the step-by-step method, and a clean Python implementation you can use in interviews.
Problem Statement
DataFrame animals +-------------+--------+ | Column Name | Type | +-------------+--------+ | name | object | | species | object | | age | int | | weight | int | +-------------+--------+ Write a solution to list the names of animals that weigh strictly more than 100 kilograms. Return the animals sorted by weight in descending order.
Quick Facts
- Difficulty: Easy
- Premium: No
- Tags: Pandas
Intuition
The constraints allow a direct scan that keeps only the essential state.
By translating the requirements into a clean loop, the logic stays easy to reason about.
Approach
Iterate through the data once, updating the state needed to compute the answer.
Return the final state after the traversal is complete.
Steps:
- Parse the input.
- Iterate and update state.
- Return the computed answer.
Example
DataFrame animals
+-------------+--------+
| Column Name | Type |
+-------------+--------+
| name | object |
| species | object |
| age | int |
| weight | int |
+-------------+--------+
Python Solution
import pandas as pd
def findHeavyAnimals(animals: pd.DataFrame) -> pd.DataFrame:
return animals[animals['weight'] > 100].sort_values('weight', ascending=False)[
['name']
]
Complexity
The time complexity is O(n). The space complexity is O(1) to O(n).
Edge Cases and Pitfalls
Watch for boundary values, empty inputs, and duplicate values where applicable. If the problem involves ordering or constraints, confirm the invariant is preserved at every step.
Summary
This Python solution focuses on the essential structure of the problem and keeps the implementation interview-friendly while meeting the constraints.