Effectively Preparing for Coding Interviews
This article provides practical tips for effectively preparing for coding interviews, focusing on using LeetCode efficiently. The advice comes from an experienced software engineer who recently accepted an offer from Facebook.
Mastering Basic Data Structures
The Importance of Foundational Knowledge
Before diving into LeetCode, ensure you have a solid understanding of basic data structures. This includes knowing how they work, the operations they support, and the time complexity of those operations.
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Even experienced engineers should review these fundamentals.
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Interview questions often probe into lower-level implementation details.
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A quick 10-minute review can prevent time-wasting mistakes during the interview.
Structuring Your LeetCode Practice
Difficulty Level
When using LeetCode, a structured approach is essential. Begin by considering the difficulty level of each question: easy, medium, or hard.
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Start with easy questions to build a foundation.
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Spend the majority of your time on medium-level questions.
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Incorporate hard questions sparingly, focusing on those that seem popular.
Why Prioritize Medium-Level Questions
Hard questions are often less effective for learning generalizable problem-solving techniques. The goal is to learn methods applicable to various unfamiliar questions.
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Many hard questions rely on specific tricks or algorithms with limited applicability.
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Focus on mastering techniques that can be applied across different problems.
Topic Coverage
Consider the topics covered by each question. Practice a few questions in each of the following areas:
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Arrays and Strings
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Dynamic Programming
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Trees and Graphs
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Binary Search
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Design
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Heaps
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Recursion
Addressing Weaknesses
Focus on the topics you find most challenging. Deliberate practice in these areas will lead to significant improvement.
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Devote time to less common topics like backtracking, linked lists, union find, and tries.
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Doing at least one question from each of these less common topics can prevent being caught off guard.
Utilizing LeetCode Features
Company Tags (Premium)
LeetCode's premium version offers company tags, allowing you to filter questions asked at specific companies. This provides insights into what to expect from interviews at those companies.
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A free alternative is searching the company name in the "Discuss" section.
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Users often share their real interview experiences in the discussion forums.
Sorting by Frequency (Premium)
Another valuable premium feature is sorting questions by frequency. This shows how often questions have been asked in real interviews.
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A high-frequency question indicates that it effectively measures a candidate's skills.
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The methods used to solve these questions are likely to be useful in real interviews.
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A free alternative is to consider the likes and dislikes count, avoiding questions with significantly more dislikes than likes.
Approaching Coding Problems
The Naive Solution
When solving a coding problem, start by considering the naive solution: how you would solve it with unlimited time and space.
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This provides a baseline for understanding the problem's complexity.
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It can also hint at potential optimization techniques.
Small Examples and Corner Cases
Solve the problem using small examples to identify patterns and generalize rules.
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Test your ideas with challenging inputs and corner cases.
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Avoid trivial examples that don't adequately test your solution.
Knowing When to Seek Help
If you're stuck after about half an hour, don't spend too long struggling.
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Read the solution or watch a video explanation, ensuring you fully understand it.
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Implement and submit the solution yourself to solidify your understanding.
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Reflect on what you missed that could have helped you solve the question independently.
Final Thoughts
Remember that coding interviews are challenging for everyone. Be patient with yourself and persistent in your preparation. Consistent effort will lead to improvement and success.