Parse Strings to Extract Payloads | Dataford Interview Questions

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Problem

Bayer systems may exchange multiple data frames in one string across surfaces such as crop-science, pharmaceuticals, and consumer-health. Parse the stream and return every payload belonging to a requested surface.

Each frame has this format:

BAYER/<surface>/<length>/<payload>

Frames are concatenated directly with no separator. The decimal length specifies the exact number of characters in payload, so the payload may contain /, spaces, or other frame-like text. A surface contains lowercase letters and hyphens. The prefix and separators are case-sensitive.

Implement extract_payloads(stream, surface) to return payloads in their original order. The input stream is guaranteed to contain only complete, well-formed frames, and surface is valid. Return an empty list when no frame matches.

Constraints

1 <= len(stream) <= 10^6
1 <= len(surface) <= 30
Each payload length is a nonnegative decimal integer no greater than 10^5
The total payload length is at most 10^6
Every frame is complete and well-formed

Function Signature

def extract_payloads(stream, surface):