Meituan AI Interview of Summer Internship for 2026

Docs

Technical Questions

Compare the pros and cons of the two solutions to the IPv4 address exhaustion problem: NAT and IPv6.

	NAT	IPv6
Pros	Can extend the life of IPv4 addresses. Allows multiple devices to share a single public IP address. More secure as it hides internal IP addresses.	Provides an unlimited number of IP addresses. Simplifies network configuration. *Better support for mobile devices and IoT.*
Cons	Can cause issues with certain applications (e.g., peer-to-peer). Adds complexity to network configuration. Lead to longer latency.	*Not widely adopted yet.* *Compatibility issues with existing IPv4 infrastructure.* *Requires updates to network hardware and software.* Security concerns due to exposure of internal IP addresses.

Describe the Linux permission system and explain how to change file permissions.

Linux permissions are divided into three categories: user (owner), group, and others, respectively represented by u, g, and o. Each category can have read (r), write (w), and execute (x) permissions, represented by the numbers 4, 2, and 1 or the letters r, w, and x. The permissions can be represented in three octal digits, where each digit represents the permissions for user, group, and others.

For example, chmod 755 file.txt sets the permissions to rwxr-xr-x, meaning the owner has read, write, and execute permissions, while the group and others have read and execute permissions.

For directories, the execute permission allows entering the directory, while the read permission allows listing its contents.

To change file permissions, you can use the chmod command followed by the desired permissions and the file name. For example:
```
chmod 644 <file_name>
chmod 755 <directory_name>
chmod 600 <secret_file, like SSH private key, etc.>
```
Also, you can use the representing letters to change permissions. For example:
```
chmod u+x <file_name>  # Add execute permission for the owner
chmod g-w <file_name>  # Remove write permission for the group
chmod o+r <file_name>  # Add read permission for others
```
Even:
```
chmod a+r <file_name>  # Add read permission for all
chmod a-w <file_name>  # Remove write permission for all
chmod +x <file_name>  # Add execute permission for all
chmod -x <file_name>  # Remove execute permission for all
```
~~I believe that I would be kicked out of LUG if I didn’t know this.~~
How to troubleshoot and avoid SQL database index failure?

A classic interview question. But I forgot to mention that the EXPLAIN statement can be used to analyze the execution plan of a query, which helps identify why an index is not being used.
Describe the reflection mechanism of Go.

Reflection in Go allows you to inspect the type and value of variables at runtime. It provides a way to dynamically access and manipulate objects without knowing their types at compile time. The reflect package provides the necessary functions and types for reflection.
How does Go’s map dynamically adjust its size?

Go’s map uses a hash table to store key-value pairs. When the number of elements in the map exceeds a certain threshold, Go automatically resizes the underlying array to accommodate more elements. This resizing process involves creating a new array with a larger capacity and rehashing the existing keys to fit into the new array.

The resizing process is done in a way that minimizes the performance impact on the program. However, it is important to note that resizing a map can be an expensive operation, so it is advisable to preallocate the map with an initial size if you know the expected number of elements.
Describe the context package in Go, what functions it provides, and give an example of its usage.

The context package in Go provides a way to manage request-scoped values, cancellation signals, and deadlines across API boundaries. It is commonly used in concurrent programming to pass context information between goroutines.

The main functions provided by the context package include:
- Background(): Returns a non-nil, empty context.
- TODO(): Returns a non-nil, empty context that can be used when you don’t have a specific context to use.
- WithCancel(parent Context): Returns a copy of the parent context with a cancellation function.
- WithDeadline(parent Context, deadline time.Time): Returns a copy of the parent context with a deadline.
- WithTimeout(parent Context, timeout time.Duration): Returns a copy of the parent context with a timeout.
Example usage:
```
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()

// Use ctx in your goroutine or function
go func() {
   select {
   case <-ctx.Done():
	   // Handle cancellation
   }
}()
```
Explain the execution order of Go’s Init() function.

The Init() function in Go is automatically executed before the main function. It is used to initialize package-level variables and perform setup tasks. The execution order of Init() functions is as follows:
1. The Init() function of the main package is executed last.
2. The Init() functions of imported packages are executed in the order they are imported.
This ensures that all necessary initialization is done before the main function starts executing.
Design a draft editing system to prevent file loss, and describe your design ideas.

An open-ended question to some extent. My local solution was based on the periodic saving feature of VSCode and Word, while the remote solution was inspired by VSCode SSH, Tencent Docs, and Zed’s collaborative editing (unfortunately, when Zed was trending, I didn’t take the time to study how it handles collaborative conflicts, so I ended up improvising with “atomic operations” and then added a straightforward “locking mechanism”). I even brought up Redis (now, the more I think about it, the more I feel something is off—was this question actually testing distributed locks?).

Experience & Lessons

Maybe I should learn more about Go features.
Review classic interview questions on a regular basis, especially some details.
In fact, just before this interview, I have asked DeepSeek some questions about context and reflect, so take each question from curiosity seriously, maybe some of them are interview questions in the future.
~~AI interviews seem to shift toward directions I can’t handle every time the questions change, so please don’t change the questions.~~