Youtube

Role: Software Engineer, L4

College: Not Specified

Interview Date: October 2023

Interview Type: Full-Time

Result: Selected

Difficulty: Medium

Rounds: 5 rounds

Topics Asked: Data Structures (Trees, Graphs, Hash Maps), Algorithms (Dynamic Programming, BFS/DFS), System Design (Video Streaming, Scalability), Behavioral (STAR method).

Experience:

This candidate successfully interviewed for an L4 Software Engineer position at YouTube in late 2023. The entire process took about 2 months from initial recruiter contact to offer. The focus was heavily on data structures and algorithms, followed by a strong emphasis on system design for large-scale applications.

Round 1: Phone Screen (45 mins)

A coding question was asked: "Given a list of words, group anagrams together." The candidate discussed different approaches (sorting characters, character counts using hash maps) and coded the hash map approach. The interviewer was interested in time and space complexity analysis, and edge cases.

Round 2: Onsite - Coding 1 (45 mins)

Question was about tree traversal and modification: "Given a binary tree, flatten it into a linked list in-place." The candidate discussed recursive and iterative solutions, with the interviewer focusing on the in-place requirement and memory efficiency.

Round 3: Onsite - Coding 2 (45 mins)

Dynamic Programming problem: "Find the maximum product subarray." The candidate initially struggled with negative numbers but eventually came up with the correct DP state tracking both max and min products, with some hints from the interviewer.

Round 4: Onsite - System Design (45 mins)

Design a system for "YouTube's 'Watch Later' functionality." This involved discussing APIs, database schema, caching, synchronization across devices, and handling millions of users. The candidate focused on scalability, consistency, and availability trade-offs.

Round 5: Onsite - Behavioral/Googliness (45 mins)

Standard behavioral questions using the STAR method. Questions included: "Tell me about a time you failed," "Describe a conflict with a teammate and how you resolved it," and "Why YouTube/Google?" The candidate also asked about team culture and current projects.

Tips: Practice LeetCode thoroughly, especially medium and hard problems. For system design, understand core concepts like distributed systems, databases, caching, and load balancing. Be prepared to explain your thought process clearly and ask clarifying questions.