This time it is Amazon Intern VO, overall it is actually still a "familiar formula":BQ+Coding, but the details can still easily widen the gap. This student was actually quite unsure at the beginning, especially his BQ expression and coding rhythm were not stable. Later, we did several rounds of mocks and sorted out the answer structure and ideas. The overall performance of these two rounds was much smoother. Let’s briefly review the content of the two rounds.
Round 1
BQ
The first round was with an old American interviewer. After a brief greeting at the beginning, we went directly to the BQ, which mainly focused on two questions: one was the experience of solving complex problems, and the other was how to deal with tight deadlines.
The essence of this type of question is still the examination of Leadership Principles. The focus is not on the story itself, but on whether there is a clear structure. The more important thing is whether you can clearly explain your decision at the time, why you did it, and the final results. If you just describe your experience in a straightforward way and do not reflect your thinking process, it will actually be difficult to get a high evaluation.
Coding: Word Ladder (BFS)
Coding is a classic Word Ladder, which is a very high-frequency graph theory BFS question.
The overall idea is to abstract the problem into an implicit graph: each word is a node, and if two words differ by only one character, there is an edge. Starting from beginWord, BFS is performed, each time trying to replace every character of the current word (26 possibilities) to generate a new word. If the new word is in the dictionary and has not been accessed, it is added to the queue and the number of steps is recorded. When endWord is encountered for the first time, the shortest path length is returned directly.
The real problem with this question lies in the details. For example, if visited is not deduplicated, it will be directly TLE, or the string processing is not efficient enough, which will affect the final performance.
Round 2
BQ
The second round also started with BQ, and the questions were changed to failure experiences and how to deal with disagreements with leaders.
This round focuses more on ownership and communication skills. The point is not whether you encountered a problem, but how you dealt with it, whether you took the initiative to advance it, and what the final result was. Many students get stuck here. The main reason is that they are not prepared in advance and it is difficult to quickly organize a logical answer on the spot.
Coding: Concatenated Words (DP)
The second round of coding is a word splicing problem, which is essentially a variation of Word Break.
The method is to first put all the words into a set, and then judge one by one whether each word can be spliced from other words. You can use DP to do it. Define dp[i] to indicate whether the first i characters can be spliced. Initialize dp[0] = true. Then enumerate the split points. As long as the previous segment can be spliced and the next segment is in the collection, the status can be updated.
There are two key points here: one is that the word itself cannot be used and needs to be removed from the set first; the other is that it must be composed of at least two words, otherwise misjudgment will occur.
Overall summary
In summary, these two rounds of interviews were very standard: the questions were not difficult, but they tested basic skills and stability. The problem for many students is not that they don’t know how to write, but that they are not stable in writing. For example, the BFS template is unfamiliar, the DP transfer is written incorrectly, or the BQ has no structure, which will directly affect the performance.
If you want to continue to prepare for Amazon or other major VOs in the future, it is recommended to focus on preparing two things: one is to practice high-frequency question types such as BFS and DP until they are close to "muscle memory", and the other is to organize the structure of BQ in advance according to Leadership Principles. As long as these two points are done well, the overall passing rate will be significantly improved.
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