Fidelity Investments Data Engineer Interview Questions and Answers

Round duration - 60 minutes
Round difficulty - Medium

Technical round with questions on DSA and OS.

Q1. 
LRU Cache Design Problem Statement
Design and implement a data structure for a Least Recently Used (LRU) cache that supports the following operations:
• get(key) - Retrieve the value associated with the...read more
Ans. 
Design and implement a Least Recently Used (LRU) cache data structure that supports get and put operations with a specified capacity.
• Implement a doubly linked list to keep track of the order of keys based on their usage.

• Use a hashmap to store key-value pairs for quick access and updates.

• When a key is accessed or updated, move it to the front of the linked list to mark it as the most recently used.

• When the cache reaches...read more
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Q2. 
Maximum of All Subarrays of Size K
Given an array of non-negative integers and an integer K representing the length of a subarray, your task is to determine the maximum elements for each subarray of size ...read more
Ans. 
Find the maximum elements for each subarray of size K in a given array.
• Iterate through the array and maintain a deque to store the indices of elements in decreasing order.

• Pop elements from the deque that are out of the current window.

• Keep track of the maximum element in each subarray of size K.

• Return the maximum elements for each subarray.
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Q3. What is virtual memory?
Ans. 
Virtual memory is a memory management technique that allows a computer to compensate for physical memory shortages by temporarily transferring data from RAM to disk storage.
• Virtual memory allows programs to use more memory than is physically available on the system.

• It helps in multitasking by allowing multiple programs to run simultaneously without running out of memory.

• Virtual memory uses a combination of RAM and disk...read more
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