Selenium Data Structures & Algorithms 3

Question 1

A Selenium page object stores element locators as key-value pairs where keys are strings and lookups must be O(1). Which structure is ideal?

Accepted Answer

HashMap

Answer

HashMap provides O(1) average-time key-based lookup using hashing, ideal for locator storage.

Question 2

In Selenium Grid, test jobs are dispatched to nodes in the order they arrive. Which data structure models this dispatch queue?

Accepted Answer

FIFO Queue

Answer

A FIFO Queue processes requests in the order they arrive, matching Selenium Grid's job dispatching behavior.

Question 3

Which traversal of a DOM-like tree structure visits a node before its children, useful for Selenium page hierarchy parsing?

Accepted Answer

Pre-order

Answer

Pre-order traversal visits the current node first, then recursively visits left and right subtrees, matching top-down DOM parsing.

Question 4

What worst-case time complexity does QuickSort have, and when does it occur?

Accepted Answer

O(n²) on already-sorted or reverse-sorted input

Answer

QuickSort degrades to O(n²) when the pivot is always the smallest or largest element, as in sorted or reverse-sorted arrays.

Question 5

A Selenium test suite tracks parent-child test dependencies. Which data structure best represents these relationships?

Accepted Answer

Directed Acyclic Graph (DAG)

Answer

A DAG represents dependency relationships without cycles, accurately modeling test prerequisites.

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