How to pass a coding test?

To pass a coding test, whether it’s for a job interview, an assessment for a class, or a coding competition, you need both a solid understanding of algorithms and data structures and strong problem-solving skills. Here's a step-by-step guide to help you prepare and succeed:

1. Understand the Test Format

Before taking the coding test, understand the specific requirements:

• Language: Know which programming languages are allowed.
• Time Limits: Practice solving problems under timed conditions.
• Types of Problems: Is the test focused on algorithms, data structures, debugging, or a mix of these?

2. Practice Common Data Structures and Algorithms

Many coding tests require knowledge of basic and advanced algorithms. Make sure to review:

• Data Structures: Arrays, linked lists, stacks, queues, hash maps, trees, graphs, and heaps.
• Algorithms: Sorting (merge sort, quicksort), searching (binary search), graph algorithms (BFS/DFS), dynamic programming, and greedy algorithms.

Resources:

• LeetCode: Focus on practicing easy, medium, and hard problems relevant to your coding test.
• HackerRank: Offers a structured way to learn and practice algorithms.

3. Study Problem-Solving Patterns

Many coding problems follow certain patterns. Familiarizing yourself with these patterns will help you quickly recognize and solve problems efficiently.

• Common Patterns: Sliding Window, Two Pointers, Top K Elements, Merge Intervals, Backtracking, Dynamic Programming.

Resource:

• Grokking the Coding Interview: This course is great for learning these common patterns.

4. Read the Problem Carefully

During the test, it’s crucial to read the problem carefully and fully understand it before jumping into coding.

• Clarify: If the platform allows, clarify ambiguities. In an interview setting, ask clarifying questions.
• Plan: Take a few moments to plan your approach before starting to code.

5. Start with a Brute Force Solution

If you’re struggling to find an optimal solution right away, start by implementing a brute force solution. While it may not be the most efficient, it will at least help you get part of the problem solved. From there, you can optimize it.

6. Optimize Your Solution

After implementing a brute force solution:

• Look for inefficiencies: Can you reduce time or space complexity?
• Time Complexity: Aim for O(n) or O(log n) solutions where possible.
• Space Complexity: Be aware of unnecessary memory usage, particularly with recursive solutions.

7. Test Your Code

Once you’ve implemented the solution, test it with different inputs, including edge cases:

• Basic Tests: Test normal cases, such as small inputs or typical ranges.
• Edge Cases: Test extreme cases, such as empty arrays, very large numbers, or duplicate elements.

8. Practice with Mock Tests

Simulate the coding test environment by practicing with timed mock tests. You can use platforms like:

• LeetCode’s Mock Interviews: Practice coding problems in a time-limited format.
• Pramp: Get real-time peer-to-peer coding practice with feedback.

9. Review Past Mistakes

After each practice test or coding session, review your mistakes. Focus on:

• Understanding why the mistake happened.
• How to avoid similar mistakes in future problems.

Resources:

• Discussion Sections: On platforms like LeetCode, review the discussion sections for different approaches to the same problem.

10. Stay Calm and Focus on One Problem at a Time

In coding tests, managing stress is essential. Break the problem into smaller parts, solve one part at a time, and avoid panicking if you get stuck.

Conclusion

To pass a coding test, build a strong foundation in data structures and algorithms, practice regularly on platforms like LeetCode and HackerRank, and take mock tests to simulate the real exam. Recognizing patterns, writing clean code, and testing your solutions are critical to success.