Reddit is a globally recognized content community platform known for its powerful back-end architecture and large-scale data processing capabilities. Its technical team advocates simplicity, engineering thinking and system stability. Many students may feel that Reddit is not a typical big factory, but in fact, its technical challenges and interview difficulty does not lose FAANG! This post will share some Reddit high-frequency interview questions, as well as some students widely recommended preparation strategies (Reddit interview tips), to help you get through!
Brief description of the interview process (SWE positions)
OA (optional): Simple algorithmic screening
VO (2 to 3 rounds)Coding + System Design
Onsite/Final (4 to 5 rounds): Coding + System Design + Behavioral
Sharing of interview questions
Sub-section post heat calculation
Background Description:
Every subreddit on Reddit sorts posts based on their hotness. Now you are asked to implement a simplified version of the heat model that, given the upvotes, downvotes, and posting time of each post, calculates its heat score and returns the top K posts.
Require:
Use the following heat function (a simplified version of Hacker News):
hot_score = (upvotes - downvotes) / (hours_since_posted + 2)^1.5
Returns the top K post IDs in descending order of hot_score.
Analog user reporting system
Background Description:
Reddit allows users to report posts that violate the rules. You need to implement a module that counts how many unique users have reported a post in a 24 hour period and can always check if the current number of reports exceeds a threshold.
Enter the operation:
report(user_id, post_id, timestamp): Record reporting
is_flagged(post_id, current_time): Determine if a post exceeds the reporting threshold (e.g. 10 reports)
Subreddit Classified Recommender System
Background Description:
Reddit wants to suggest similar communities based on the subreddits where users are active. Please design a simple data model & algorithm to implement "subreddits you might be interested in".
Reference design elements:
Each subreddit can be represented by keywords
Historical user access behavior as input
Returns a list of subreddits with a high degree of overlap with their interests
How to go about preparing for a Reddit interview?
Reddit's engineering culture not only focuses on algorithmic ability, but also emphasizes whether the code can be implemented, maintained, and have an impact on users. In the interview, we need to be able to combine "Reddit is a community content platform" to understand the essence of the topic.
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