WXG First-Round Interview: 60 Questions from Algorithms to Agent Design

Interview Overview

Interview date: September 21. The candidate describes a comprehensive first-round interview at WXG (WeChat Group) covering internship logistics, projects, fundamentals, algorithms, and scenario questions.

Introduction & Logistics

Self-introduction

Availability: start date and internship duration

Current internship status at ByteDance

Team responsibilities and personal role

Team development process and cadence

Algorithm Questions

IP + port to uint64: Convert an IP address and port number into a single 64-bit unsigned integer.

Fold linked list: Reorder a singly linked list by folding it in half (e.g., L0→Ln→L1→Ln-1…).

Uniform sampling with rand16(): Given a generator rand16() producing uniform integers in [0, 65535], write a function to uniformly sample 10,000 employees from IDs 0 to 299,999.

System Architecture & Optimization

Overall system architecture

Purpose and role of a specific platform (name masked)

Performance optimization approach for reducing creation latency

Further optimization space for the same latency case

Challenging Projects & Credential Hosting

Most challenging task encountered

Complexities in credential hosting (details masked)

Agent & AI Tooling

Key considerations and steps for building an Agent (referencing a resume project about transferring to human agents)

How to construct Skills within an Agent

Daily AI products/tools used in development

Primary AI coding tools used

Whether the company provides AI coding tools or they are self-purchased

Main large models used

Attention to model usage cost / token cost

Large Model Fundamentals

Understanding of hallucination: causes and why it occurs

General training process of large models

RAG & Vector Retrieval

Basic principle of knowledge base / RAG (Retrieval-Augmented Generation)

Principles of vector retrieval algorithms / indexes mentioned

Search & Recommendation

Traditional search engine implementation

Collaborative filtering principle

Concrete implementation steps for a collaborative filtering recommender

System Design Scenario

Design the overall architecture of a 12306 ticketing system

Additional roles of message queues beyond those already mentioned

Language-Specific Questions

Java vs. Go usage in resume and ByteDance internship

Reason for using Java in written test instead of Go

C++ experience

C++ & operator (reference)

C++ && (rvalue reference)

C++ smart pointers

Redis Internals

Basic data types and underlying implementations String implementation: SDS (Simple Dynamic String) Set implementation

MySQL & B+ Tree

General MySQL knowledge

B+ tree introduction

Time complexity of insert, delete, search, update in B+ tree

Why InnoDB uses B+ tree over other structures

Why not hash table as primary index

Why not B-tree

Why not red-black tree

Concurrency conflicts in B+ tree under concurrent access

Lock application during B+ tree CRUD operations

Big Data & Design Patterns

Familiar big data processing components

Common design patterns known

Real-world example of applying a design pattern

Reflection & Reverse Questions

Learnings from the internship

Candidate's questions for the interviewer