TikTok SWE AI Agent Intern, second-round interview report.
This was the second round, and the entire conversation was in Mandarin.
I started with a self-introduction, followed by a deep dive into my research project.
Fundamentals / business design
How HTTPS works.
Explain the TLS/SSL handshake process and CA certificate validation in detail.
Follow-up: During data transmission, is symmetric or asymmetric encryption used?
My answer: Asymmetric encryption is only used during the handshake to negotiate a symmetric key. The actual communication afterward uses symmetric encryption for high performance and low latency.
Follow-up: How do packet-capture tools such as Charles and Wireshark capture and decrypt HTTPS traffic?
My answer: Install and trust a local man-in-the-middle root certificate, allowing encrypted traffic to be decrypted and forwarded through a proxy.
The complete compilation pipeline, from source code to an executable:
Preprocessing -> compilation -> assembly -> linking -> the final executable.
Project details and troubleshooting
They dug into my iOS development project and asked how I would investigate and debug an out-of-memory problem in an iOS app.
Algorithms / LeetCode
Problem: Paths in a binary tree whose sum equals a specified value.
It was LeetCode's Binary Tree Path Sum, with the only difference being that I had to save and output all the paths.
I was told to assume that a node class already existed and write the code directly. We didn't run it at the end.
Solution: Standard recursive DFS and backtracking. Since it was a classic LeetCode problem, I finished writing it quickly, in about seven minutes.
Then came Q&A.
Discussion
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