solving test task 1 and 2

[hafizzz24498]

Submit coding challenge for backend developer from Hafiz Pangteh

[Copilot]

Pull Request Overview

This PR submits solutions for two backend developer coding tasks and accompanying documentation.

• Implement run-length encoding with Unicode surrogate pair support.
• Fix thread-safety bug in BuggyCounter by using atomic operations.
• Add solution notes in SOLUTIONS.md.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 6 comments.

File	Description
tasks/01-run-length/csharp/Rle.cs	Added Encode implementation handling surrogate pairs.
tasks/02-fix-the-bug/csharp/BuggyLib/BuggyCounter.cs	Replaced manual increment + Thread.Sleep(0) with Interlocked.Increment.
SOLUTIONS.md	Added solution notes and explanations for both tasks.

[Copilot]

Interlocked.Increment returns the incremented value, but the original code returned the previous value. If you need to preserve the original ID sequence starting from 0, consider returning Interlocked.Increment(ref _current) - 1 or adjust initialization/tests accordingly.

Suggested change

	return Interlocked.Increment(ref _current);
	return Interlocked.Increment(ref _current) - 1;

[Copilot]

This concatenates strings and integers via +, causing an intermediate allocation. Consider using result.Append(prevChar).Append(count); to reduce allocations.

Suggested change

	result.Append(prevChar + count);
	result.Append(prevChar).Append(count);

[Copilot]

Similar to above, replace with result.Append(prevChar).Append(count); to avoid creating an extra string.

Suggested change

	result.Append(prevChar + count);
	result.Append(prevChar).Append(count);