A developer needs to store a collection of unique email addresses while ensuring fast lookups.

Comprehensive and Detailed In-Depth Explanation:

In UiPath, when we need to store unique values and allow fast lookups, the best data structure is HashSet(Of String).

Step-by-Step Execution Guide:

Declare a HashSet in UiPath:

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Dim emailSet As New HashSet(Of String)

Add unique email addresses:

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emailSet.Add("user1@example.com")

emailSet.Add("user2@example.com")

emailSet.Add("user1@example.com") ' Duplicate entry will be ignored

Check if an email exists:

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If emailSet.Contains("user2@example.com") Then

Console.WriteLine("Email exists!")

End If

???? HashSet ensures that duplicates are automatically ignored and lookups are extremely fast (O(1) complexity).

Real-World Use Case:

???? Email Filtering System

A bot processes thousands of emails and must ensure that duplicate addresses are ignored.

Using a List(Of String) would require manual duplicate checking, whereas HashSet(Of String) automatically prevents duplicates.

Why the other options are incorrect?

❌ A. Array – Arrays have fixed sizes and do not support efficient lookups or uniqueness checks.

❌ B. List(Of String) – Lists allow duplicates, requiring manual checking (.Contains()) before adding items.

❌ C. Dictionary(Of String, Boolean) – Although it can simulate a HashSet, it requires more memory due to key-value pairs.

✅ Reference:

UiPath Documentation: Collections and HashSet

Microsoft VB.NET Docs: HashSet Class