Max Length Token

A medium Python interview practice problem on DataDriven. Write the Python and run it against test cases, with instant feedback.

Domain
Python
Difficulty
medium
Seniority
L3

Problem

Given a string, split on whitespace and return the longest token. If multiple tokens tie for longest, return the first one.

The longest token wins.

Example 1

Input:

s = "the quick brown fox"

Output:

"quick"

Example 2

Input:

s = "hello"

Output:

"hello"

Worked solution and explanation

Why this problem exists in real interviews

Finding the longest word tests string splitting and tracking a running maximum with a tiebreaking rule. It is a basic string processing task that checks attention to detail on ties.

Break down the requirements

Step 1: Split the string by whitespace

Use str.split() to tokenize. This handles multiple spaces correctly.

Step 2: Track the longest word, preferring the first on ties

Use > (strict greater than) when comparing lengths so that earlier words win ties.

The solution

Whitespace tokenization with length tracking
def longest_word(s):
    words = s.split()
    best = words[0]
    for i in range(1, len(words)):
        if len(words[i]) > len(best):
            best = words[i]
    return best

Common follow-up questions