Introduction

I recently interviewed for a software engineering position at Amazon. During the interview, I was presented with an intriguing problem involving compound words in a list. In this post, I will share my experience, detailing the interview process and the solution I proposed.

The Problem

The interviewer presented the following problem:

Problem Statement:

You are given a potentially large list of words. Some of these are compound words, where all parts are also in the list. Your task is to identify all combinations where one word is a composite of two or more words from the same list.

Example List: [rockstar, rock, star, rocks, tar, rockstars, super, highway, high, way, superhighway]

Output: [[rock, star], [super, highway], [super, high, way],...]

The Interview Process

The interview began with a brief introduction, and then the interviewer moved straight to the coding problem.

Interviewer: "Let's jump into the coding exercise. You're given a list of words, and some of these words are compound words made up of other words in the list. Can you identify all such compound words and their components?"

Me: "Sure, sounds interesting. Could you please clarify if we need to consider words that are composed of more than two parts?"

Interviewer: "Yes, you should consider all possible combinations, not just pairs."

I then shared my screen and started by writing down the problem statement to ensure I understood it correctly.

Initial Thoughts and Approach

Me: "I'll start by building a hash table to store all the words for quick lookup. Then, I'll iterate over each word and try to split it into all possible combinations of subwords. For each split, I'll check if the subwords exist in the hash table."

Interviewer: "That sounds like a good plan. How will you handle the recursive nature of finding subwords?"

Me: "I'll implement a helper function to recursively check if a word can be decomposed into valid subwords."

The interviewer nodded in agreement, and I began coding.

Implementing the Solution

I started by writing the main function to create the hash table and iterate over each word:

Me: "Here's the main function. It checks each word by splitting it at different positions and seeing if both parts are in the hash table. If they are, or if the suffix can be recursively decomposed, the word is considered a compound word."

Interviewer: "Great. Can you explain the logic of the is_compound function?"

Me: "The is_compound function splits the word at every possible position, creating a prefix and a suffix. It checks if the prefix is in the word set and if the suffix is either in the word set or can be further decomposed recursively. If both conditions are met, it returns True, indicating the word is a compound word."

Interviewer: "Looks good. Your approach is efficient and handles the recursive checks well. Do you have any thoughts on optimizing it further?"

Me: "One potential optimization could be to use memoization to store results of previously computed subwords, which would avoid redundant calculations and speed up the process."

Interviewer: "Excellent point. Memoization could indeed improve the performance. Another thing to consider is handling edge cases, such as very long words or lists with no compound words."

Me: "Absolutely. Handling edge cases is crucial to ensure robustness. I would also consider using dynamic programming to store intermediate results and avoid redundant computations."

Conclusion

The interview wrapped up with a brief discussion on possible optimizations and additional edge cases. This problem was a great exercise in understanding how to handle recursive checks and efficiently manage lookups using hash tables. The experience was challenging but rewarding, and it provided a good insight into the problem-solving approach expected at Amazon. Overall, it was a positive experience, and I felt more confident in my ability to tackle similar problems in the future.

Through our powerful interview support, the candidate successfully navigated these interview questions. The analysis and discussion not only showcased the candidate's programming skills but also demonstrated their clear problem-solving approach and effective communication abilities. These insights are valuable not only for tackling Meta's interviews but also for enhancing our capability to solve real-world programming challenges. Good luck to everyone with your interviews!

经过我们的强力面试辅助，候选人通过这些面试题的解析和沟通，面试官不仅了解了候选人的编程能力，也看到了我在解决问题过程中清晰的思路和有效的沟通技巧。这些不仅有助于应对 Meta 的面试，同时也能提升我们解决实际编程问题的能力。祝大家面试顺利！

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