Among the many tech companies thatMeta(Formerly Facebook) has always been known for its high-intensity and systematic interview process. Especially the VO session, as the key level before getting an offer, many students said, "The difficulty is not low, but it is a great exercise for thinking." In this article, we will share a few Meta VO high-frequency questions with real interview experience, which will help you understand the style of questions and improve the preparation efficiency.
Meta VO Interview Process Overview
- CV: from the resume to wait until the interview notice may take three days to three months (the famous long time line), but need to pay attention to a job hang up if there will be a frozen period, can not be submitted to the same type of position.
- Telephone initial screening (Optional): HR lady / little brother to call you, is to confirm your visa status, professional background and interview time. This time to show confidence and cordial Oh, let HR feel your enthusiasm and sincerity for this job. At this stage, there is usually no technical interview!
- Online Quiz (OA) / Technical Phone Interview: medium difficulty, 4 questions in 70 minutes. Usually HR will send you the OA link on the same day or the next day, which is valid for one week, so start solving mode! Or an interview invitation (phone interview) phone interview: engineers ask you to chat, do two questions which may be totally unrelated or one question, and then ask to FOLLOW UP. no matter intern or new grad, the algorithmic interview level is the same difficulty.
- Virtual Onsite (VO): Generally, HR will arrange Virtual Onsite after two weeks, which may be three rounds of code + one round of behavioral Q&A or one round of system design. Starting from 2023, it is now possible to negotiate with HR to complete the interview in two days (before it was done in one day).
Meta VO Selected Questions
After describing the overall interview process at Meta, let's now take a look at the actual Meta VO interview questions.
1. Merging left and right side views of binary trees
Given a binary tree, imagine yourself standing on the left side of it, return the values of the nodes you can see ordered from bottom to top, then switch to right side of the tree, and return the values of the nodes you can see ordered from top to bottom.
# Binary Tree.
# ----> 1
# / \ \
# ----> 2 3 6 5 4 1
# / \ \
# ----> 2 3 5 <---
# Answer: [5, 2, 1, 3, 5]A frequent meta vo question to find the first node visible from bottom to top on the left and top to bottom on the right. The idea is to maintain two dictionaries, one for the first and one for the last occurrence of the node in each depth. Then the answer is a combination of the first and second dictionaries.
2. Vertical order traversal of binary trees
Given the root of a binary tree containing integers, print each column from left to right, and within each column print the values from top to bottom.
6 / \ 3 4 / \ / \ 5 1 0 / \ 2 / / / / / / / / / / / / / / / / / / / / / / / / 9 8 \ 7 Output: 5 9 3 2 6 1 7 4 8 0
Points of clarification
The first question is whether there is an empty tree, which is a common edge case in binary trees. The second question is how to get the result: return a list or just output it in the procedure.
Thoughts:
We need to output the value of each node from left to right and from top to bottom. Obviously we should group the nodes by column, and then we just need to make sure that each column is internally accessible from top to bottom. Obviously, we need to use the bfs algorithm to search. Because of the uncertainty of the column range, we can assume that the column of the root node is 0. Then the column needs to be decreased by 1 when we move to the left child node, and increased by 1 when we move to the right child node. When the bfs is finished, we iterate through the hashmap once to get the smallest and the largest columns, and then we use a two-tiered loop to generate the final result. Then use a double loop to generate the final result.
Third session code hammering... hands must be fast Fourth session dry run + space-time complexity
3. Meta VO System Design
This round is supposed to be training, a smiling Japanese uncle shadow a Chinese guy.
The title is. Design a ticketmaster.
I wanted to follow Alex Xu's formula, but he said, "Let's not waste time on back of the envelope calculations, forget about distributed system, let's just sort out the user flow and draw a diagram for each component". We'll just organize the user flow and draw a diagram for each component.
The requirements are as follows:
- How to handle the scenario of a large number of people grabbing tickets in a short period of time.
- How to buy tickets interface has a timeout, more than a certain period of time did not pay how to deal with
- What happens when the tickets are sold out?
- How to make sure that the person who pays gets the ticket
- How to implement a waitlist that notifies the first person on the waitlist if someone bounces a check?
Tips from seniors and juniors
Coding is not about writing fast, but logic must be clear!
Meta interviewers focus more on how you think than how quickly you finish writing. It is recommended that you write and explain your answer as you go along, so that each step shows that you are thinking about boundary conditions.
System Design Don't come up with an architecture diagram right off the bat!
You can first Clarify the scene, then discuss it in modules, and finally give the architecture diagram to finish. The more clear logic, the easier the interviewer will recognize your ability.
Don't ignore the Behavioral interview!
Meta emphasizes teamwork and impact, and each question tries to give real-life examples of how you solved a problem and impacted your team using the STAR rule.
It doesn't matter if the English is not perfect, the point is to have a clear structure.
Many students will write their STAR bullet points in advance of the interview, so it will be more natural to practice a few times.
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