Google SDE Virtual Interview (VO), Experience & Questions

This experience has made me realize that while programming skills are fundamental, theProblem solving ideas and clear communicationEqually important, if not more favored in some parts of the process. Interviewers value how you think and how you articulate. The difficulty of the programming questions is medium to high, so if you keep up some algorithmic practice on a regular basis, you should be able to cope with them. However, the key lies in the ability to quickly make sense of a new problem when faced with it, and to perform a thorough complexity analysis and edge case discussion after writing the code.

Next, I will share the practical experience of this interview and some core exam questions, which I hope will be helpful to those who are preparing for the Google interview.

Google Interview Process Review

This VO interview is divided into two closely related parts:

• Part I: Behavioral Interviewing (BQ) This section focuses on assessing yourCommunication skills and structured thinking. Interviewers are not interested in a standard answer, but in how you organize your language and clearly articulate your past experience. They may ask questions like, "How do you balance efficiency and quality when a project is under deadline pressure?" or "How do you handle disagreements with project managers on technical decisions? They want to see you demonstrate organization, self-reflection, and growth, not just recite predetermined answers.

• Part II: Algorithm Questions (Coding) This session usually consists of two algorithmic questions with several follow-up questions. The questions themselves will not necessarily be very complex, but will focus more on your ability to quickly understand the problem, come up with a reasonable solution, and perform a detailed complexity analysis and optimization after implementation. Some of the follow-up questions will lead you to think about what the solution does inscalability maybeedge cases Under the performance. Interviewers are often impressed if they can take the initiative to add these points of reflection to their logical clarity.

Interview process recollection

The entire interview was divided into two parts: first a behavioral interview, followed immediately by programming questions.

Behavioral interview component

In the first question, the interviewer asked: "How do you deal with a system that you don't technically agree with, but has been implemented for some time? How would you handle it?"

My first thought at the time was to avoid directly dismissing the work of my predecessors. I emphasized the strategy of understanding, respecting, and re-proposing. I replied that I would first delve into the historical background and original design of the system, communicating with the original developers to understand their considerations. Then, I would propose a new solution and use data and test results to show the comparison between the old and new solutions in terms of performance, maintainability, and so on, and invite discussion. This not only shows respect for the existing results, but also pushes the team to make better decisions.

Question #2: "Describe a project that you led the development of and what role you played in it? How would you measure its success?"

Instead of answering the question "What did I do?", I first described the background and challenges of the project. Then, I elaborated how I drove the project forward step by step, from technology selection, architecture design to implementation. When measuring success, I not only mentioned the technical metrics (e.g., how much performance was improved), but also emphasized the business impact (e.g., user growth due to new features) and the positive impact on teamwork. In this way, I showed that I was not only the technical implementer, but also the project driver and leader.

Programming questions section

First question: "Given a binary tree, determine whether a given array is a subtree of one of itshierarchical traversal."

My first reaction was to useBreadth-first search (BFS) to solve. I need to traverse the entire tree and try to match the given array at every node. Specifically, when the BFS traverses any node, I start the BFS over again with that node as the root of the subtree and compare it to the target array.

I was thinking that it would be very inefficient to just copy the subtree and do BFS. So I changed my mindset: while the main BFS traversed the tree, when I encountered a node with the same value as the first element of the array, I started a new, separate BFS thread to synchronize the match. If this new thread traverses the array completely, and the node values from the hierarchical traversal match the array exactly, then I've found the solution. This "synchronized matching" idea avoids a lot of double-counting and extra space overhead.

Second question: "Given a $n$ array of numbers, find the number of all the numbers in the array for theLeast Common Multiples (LCM)."

I first thought of a plain idea for this question: traverse from 1 until you find the first number that is divisible by all the elements in the array. But this was obviously too slow. It immediately occurred to me that I could use the mathematical property that $LCM(a,b)=(a\ast b)/GCD(a,b)$which $GCD$ begreatest common divisor GCDThe

So I broke the question down into:

1. Find all the numbers in the array of $GCD$The

2. Using the formula, the problem is transformed into finding LCM(LCM(a1​,a2​,…,an-1​),an​). I first implemented a program to find two numbers $GCD$ (used form a nominal expression)Euclid's algorithmand then use a loop to iterate through the entire array of $LCM$. During the implementation, I needed to be aware of numerical overflow issues, so I calculated the $a\ast b$ Before dividing by $GCD$namely $LCM=(a/GCD(a,b))\ast b$The

progress report

The interviewer pursued the question:

1. "What problems does your LCM algorithm encounter when dealing with large numbers? How can you solve it?" I answered: if the number in the array is very large, or if there are many array elements, the intermediate result may be out of range of the standard integer type. The solution is to use theBigInteger to process to ensure that the calculations are correct.

2. "How does your algorithm handle it if the array contains 0 or a negative number?" I answered: If the array contains 0, the LCM is undefined and needs to be handled specially, either by throwing an exception or returning a specific value. If it contains negative numbers, I can take their absolute values before calculating, since the LCM is usually defined as positive.

Interview Summary

The overall difficulty of this interview was moderate. The behavioral interview tested logical thinking and communication skills, while the programming questions focused more on the flexible application and optimization of basic algorithms. When faced with a dilemma, instead of sticking to my initial inefficient thinking, I found a more elegant solution by deeply analyzing the nature of the problem.

This experience has made me even more convinced that an interview is not only a test of knowledge, but also a comprehensive test of adaptability and logical expression. Even if you brush up a lot of questions, if you can't clearly explain your thoughts during the interview, you may still lose the battle. Therefore, when preparing for an interview, in addition to practicing algorithms, you must also practice how to communicate with people in a clear and organized manner.