Today to update the information is about meta, recently the efficiency of the meta has become very low, these two days a lot of reschedule cases, and many cases face no reply. The case of reschedule, and a lot of case interviews have not heard back, some hr explicitly said that the decision may be delayed until after the year, we do not worry about it.
The first round is white male, two leetcode tag questions. We use python, for what it is emphasized today, burying an ambush.
Meta VO
The first question of Meta's interview was easy
We have a nested list structure containing both integers and sub-lists (nested arrays). Each integer's contribution to the final sum is multiplied by the depth level at which the integer is found. The depth of the top-level integers is 1, and if we go one level deeper, the integers there have a depth of 2, and so on. The depth of the top-level integers is 1, and if we go one level deeper, the integers there have a depth of 2, and so on. We need to compute the sum of all integers, each weighted by its We need to compute the sum of all integers, each weighted by its depth.
The key message of Clarify is that the depth is not from the first line, and you need to pay attention to the boundary condition that is empty. With recursion, the main function sets a dfs with depth, then code + dry run, adding up to about ten minutes and seconds.
The detailed idea is to DFS traverse the list:
- Checks the elements in the list one by one.
- If the element is an integer, multiply its value by the current depth and accumulate to the sum.
- If the element is a sublist, continue DFS while adding 1 to the depth.
- Finally, just calculate the weighted value directly and return it.
Focus on the second question
You are given a string Q consisting of parentheses () And []. A string of this type is said to be correct: (a) if it is the empty string
(b) if A and B are correct, AB is correct.
(c) if A is correct. (A) And [A] are correct.
Write a program that takes a sequence of strings of this type and check Your program can assume that the maximum string length is 128.
The topic is balancing brackets and the method given is the stack+set solution. The time and space complexity of this solution is O(n), because the said writing will be fast. We presuppose that the interviewer will immediately ask if there is a space O(1) method. It's the leetcode solution that searches forwards and backwards. But you need a temp to store the results. The interviewer understands the algorithm, but doesn't get the need for a list.
I was interrupted while knocking and said that having RESULT to store the result doesn't count as O(1). We provided a python solution, and python strings are immutable, so changing the input in place is also extra space complexity. Then the interviewer manually changed the input to mutable (list).
After knocking, the interviewer asked empty case, said normal processing return empty, then he did not understand python, asked the following line of the third parameter is what, we said it is back step, for read index in range(length-1,-1,-1): he felt that this line of code can deal with empty case is very magic, then I explained how this line of code handles the empty case.
He asked if you knew that from the beginning." "Yes, I knew it from the beginning. It's the best practice for traversing a list in reverse."
The interviewer was very pleased, perfect .
Meta Systems Design Interview (SD)
The system design session is usually 45 minutes long and examines your system understanding, product capability design, and other issues. System design involves demonstrating how you think in large-scale system architecture.
Design a ticket master.
Let's sort out the user flow and just draw a diagram of what each component has.
The requirements are as follows:
- How to handle scenarios where a large number of people grab tickets in a short period of time
- How to buy tickets interface has a timeout, after 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 prioritizes notification to the first person on the waitlist if someone bounces a check?
These are the VO questions shared for this Meta two rounds of Coding and one round of System design.
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