How do you solve Display the First Three Rows on LeetCode?

Display the First Three Rows (LeetCode #2879) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n) time complexity and O(n) space complexity. Key insight: Using built-in functions can greatly simplify code and improve performance.

What is the brute force solution for Display the First Three Rows?

The brute force approach for Display the First Three Rows is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute-force approach involves manually iterating through the DataFrame and collecting the first three rows. This is straightforward but inefficient for larger datasets. The optimal Optimal Solution approach improves this to O(n).

What are the interview tips for Display the First Three Rows?

Always mention edge cases and how your solution handles them. Explain your thought process clearly while coding. Practice using built-in functions to improve efficiency.

What are common mistakes when solving Display the First Three Rows?

Failing to consider edge cases, such as when the DataFrame has fewer than three rows. Not utilizing built-in functions that can simplify the task.

#2879

Display the First Three Rows

Easy

ArrayDataFrame Manipulation

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

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

💡

Intuition

Time O(n)Space O(n)

The optimal solution leverages built-in functions to directly access the first three rows of the DataFrame, making it efficient and concise.

⚙️

Algorithm

2 steps

1Step 1: Use the built-in method to select the first three rows of the DataFrame.
2Step 2: Return the result directly.

solution.py13 lines

1# Full working Python code
2import pandas as pd
3
4df = pd.DataFrame({
5    'employee_id': [3, 90, 9, 60, 49, 43],
6    'name': ['Bob', 'Alice', 'Tatiana', 'Annabelle', 'Jonathan', 'Khaled'],
7    'department': ['Operations', 'Sales', 'Engineering', 'InformationTechnology', 'HumanResources', 'Administration'],
8    'salary': [48675, 11096, 33805, 37678, 23793, 40454]
9})
10
11# Optimal solution
12first_three_rows = df.head(3)
13print(first_three_rows)

ℹ

Complexity note: The time complexity is O(n) because we are accessing the first three rows directly, which involves iterating through the DataFrame. The space complexity is O(n) as we store the rows in a new structure.

1Using built-in functions can greatly simplify code and improve performance.
2Understanding the structure of DataFrames is crucial for efficient data manipulation.

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