JI: Implementing a document versioning system

You are tasked with implementing a document versioning system. Each document has multiple versions, and each version is represented by a timestamp (an integer) and the content (a string). The system should support the following operations: 1. Add a new version of a document 2. Retrieve the content of a document at a specific timestamp For retrieval, if there’s no version exactly at the requested timestamp, return the content of the most recent version that was created before or at the requested timestamp. If there are no versions before the requested timestamp, return an empty string.

Input:
addVersion (10, “Hello”)
addVersion (20, “Hello World”‘)
getContent (15)
getContent (5)
getContent (20)
Output:
“Hello”
""
“Hello World”

Explanation: Note that versions aren’t added in order. At timestamp 50, we have an exact match with “Outline”. At timestamp 90, the most recent version is at timestamp 50. At timestam 150, the most recent version is at timestamp 120 with “Second draft”.

Requirements

1. Implement a DocumentSystem class with methods add Version (timestamp, content) and getContent (timestamp)
2. The addVersion method adds a new version with the given timestamp and content
3. The getContent method retrieves the content at the specified timestamp or the most recent version before it
4. If no version exists before or at the requested timestamp, return an empty string
5. Timestamps are positive integers and may not be added in chronological order
6. Optimize for efficient retrieval operations