Launching soon! The AI-powered interview tool – See it in action
Launching soon! AI-powered interview tool – View demo
Longest Substring Without Repeating Characters Test | Pre-employment assessment - Testlify
Back to Test Library

Longest Substring Without Repeating Characters Test

Overview of Longest Substring Without Repeating Characters Test

The goal is to find the length of the longest substring within a given string that does not contain any repeating characters.

Skills measured

  • Sliding Window
  • Hashing
  • String

Available in



Coding Test


30 Mins





Use of Longest Substring Without Repeating Characters test

The solution uses a sliding window technique, where the window is defined by the left and right pointers. The map helps to keep track of the characters encountered in the current substring. By moving the left and right pointers accordingly, we ensure that the substring remains without repeating characters, and we update the max_length whenever a longer non-repeating substring is found.

Relevant for

  • Software Developer
  • Software Engineer
  • Software Programmer

Hire the best,
every time,


Customer satisfaction

Testlify helps you identify the best talent from anywhere in the world, with a seamless experience that candidates and hiring teams love every step of the way.


Sliding Window

The Sliding Window technique is an important skill covered in the Longest Substring Without Repeating Characters problem. It involves maintaining a window of elements in the array and adjusting the window size based on certain conditions. This technique is crucial for efficiently solving problems that involve finding substrings or subarrays with specific properties, such as the longest substring without repeating characters. By using the Sliding Window technique, we can optimize the time complexity of our algorithm and efficiently find the desired solution.



In the Longest Substring Without Repeating Characters problem, hashing is a crucial skill used to efficiently keep track of the characters that have been encountered in the current substring. By utilizing a hash table or set to store the index of each character, we can quickly determine if a character has already been seen and adjust the starting index of the substring accordingly. This helps in maintaining a sliding window approach to find the longest substring without repeating characters. Hashing allows us to achieve a time complexity of O(n) for this problem, making it a key skill to master for optimal performance.



The String skill covered in Longest Substring Without Repeating Characters involves identifying and maintaining a substring without any repeating characters. This skill is important as it helps in efficiently solving problems related to finding the longest substring without repeating characters, which is a common problem in string manipulation. By understanding and implementing this skill, one can improve their ability to handle and manipulate strings effectively, making them better equipped to tackle more complex programming challenges involving strings.

The Longest Substring Without Repeating Characters test is created by a subject-matter expert

Testlify’s skill tests are designed by experienced SMEs (subject matter experts). We evaluate these experts based on specific metrics such as expertise, capability, and their market reputation. Prior to being published, each skill test is peer-reviewed by other experts and then calibrated based on insights derived from a significant number of test-takers who are well-versed in that skill area. Our inherent feedback systems and built-in algorithms enable our SMEs to refine our tests continually.

subject matter expert

Why choose Testlify

Elevate your recruitment process with Testlify, the finest talent assessment tool. With a diverse test library boasting 1500+ tests, and features such as custom questions, typing test, live coding challenges, Google Suite questions, and psychometric tests, finding the perfect candidate is effortless. Enjoy seamless ATS integrations, white-label features, and multilingual support, all in one platform. Simplify candidate skill evaluation and make informed hiring decisions with Testlify.

Frequently Asked Questions (FAQs)

Want to know more about Testlify? Here are answers to the most commonly asked questions about our company

Yes, Testlify offers a free trial for you to try out our platform and get a hands-on experience of our talent assessment tests. Sign up for our free trial and see how our platform can simplify your recruitment process.

To select the tests you want from the Test Library, go to the Test Library page and browse tests by categories like role-specific tests, Language tests, programming tests, software skills tests, cognitive ability tests, situational judgment tests, and more. You can also search for specific tests by name.

Ready-to-go tests are pre-built assessments that are ready for immediate use, without the need for customization. Testlify offers a wide range of ready-to-go tests across different categories like Language tests (22 tests), programming tests (57 tests), software skills tests (101 tests), cognitive ability tests (245 tests), situational judgment tests (12 tests), and more.

Yes, Testlify offers seamless integration with many popular Applicant Tracking Systems (ATS). We have integrations with ATS platforms such as Lever, BambooHR, Greenhouse, JazzHR, and more. If you have a specific ATS that you would like to integrate with Testlify, please contact our support team for more information.

Testlify is a web-based platform, so all you need is a computer or mobile device with a stable internet connection and a web browser. For optimal performance, we recommend using the latest version of the web browser you’re using. Testlify’s tests are designed to be accessible and user-friendly, with clear instructions and intuitive interfaces.

Yes, our tests are created by industry subject matter experts and go through an extensive QA process by I/O psychologists and industry experts to ensure that the tests have good reliability and validity and provide accurate results.

Hire with Facts, not Fiction.

Resumes don’t tell you everything! Testlify gives you the insights you need to hire the right people with skills assessments that are accurate, automated, and unbiased.

©2024 Testlify All Rights Reserved

Please enable JavaScript in your browser to complete this form.


[fluentform id=”23″]

Get 40% off on your first year’s billing!

Hurry and make the most of this special offer before it expires.

New customers only.

[fluentform id=”21″]

Test library request

These are upcoming tests. If you wish to prioritize this test request, we can curate it for you at an additional cost.

Please enable JavaScript in your browser to complete this form.
No settings found for the grid #1.