What strategy would you employ to write a function that converts a nested list of integers into a single list, and also its async/await version?

Question Analysis

The question asks you to come up with a strategy to write a function that takes a nested list of integers (i.e., a list containing other lists of integers) and flattens it into a single list of integers. Additionally, you are required to provide an asynchronous version of this function using async/await. This will test your ability to handle nested data structures and your understanding of Python's asynchronous programming capabilities.

Answer

Synchronous Version

To flatten a nested list, you can use a recursive approach or a stack-based iterative approach. The recursive approach is more straightforward:

1. Base Case: If the element is an integer, add it to the result list.
2. Recursive Case: If the element is a list, recursively flatten it and add its elements to the result list.

Here's a simple implementation:

def flatten(nested_list):
    result = []
    for element in nested_list:
        if isinstance(element, list):
            result.extend(flatten(element))
        else:
            result.append(element)
    return result

Asynchronous Version

To convert this function into an asynchronous one, let's simulate an asynchronous operation (like an I/O-bound task). We can use asyncio.sleep() to mimic this behavior.

1. Mark the function with the async keyword.
2. Use await with an asynchronous operation inside the function.

Here's how you can implement it:

import asyncio

async def async_flatten(nested_list):
    result = []
    for element in nested_list:
        await asyncio.sleep(0)  # Simulating asynchronous operation
        if isinstance(element, list):
            flattened = await async_flatten(element)
            result.extend(flattened)
        else:
            result.append(element)
    return result

# Usage example
# asyncio.run(async_flatten([[1, 2], [3, [4, 5]]]))

Key Points:

• Synchronous Function: Uses recursion to handle nested structures.
• Asynchronous Function: Introduces async behavior using await to handle potential I/O-bound tasks, although this example uses asyncio.sleep() for demonstration purposes.