TikTok Intern Software Engineer Interview Experience — AI Agent Second Round in Mandarin

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.