CARS24 Software Developer Interview Questions, Process, and Tips

Q1. Implement an immutable class.
Ans. 
An immutable class is a class whose instances cannot be modified after creation.
• Use final keyword for class declaration to prevent inheritance

• Make all fields private and final to prevent modification

• Do not provide setter methods, only getter methods should be used
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Q2. Implement a springboot service that intercepts http requests.
Ans. 
Implement a Springboot service to intercept HTTP requests.
• Create a Springboot application with necessary dependencies.

• Implement a custom interceptor by extending HandlerInterceptorAdapter.

• Override preHandle and postHandle methods to intercept requests and responses.

• Register the interceptor in the WebMvcConfigurerAdapter configuration class.
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Dsa question based on dp

Q1. Implementation of LRU cache
Ans. 
LRU cache is a data structure that stores the most recently used items, discarding the least recently used items when full.
• Use a doubly linked list to keep track of the order of items based on their usage.

• Use a hash map to quickly access items in the cache.

• When a new item is accessed, move it to the front of the linked list. If the cache is full, remove the item at the end of the list.
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Q2. Implementation of HashMap
Ans. 
HashMap is a data structure that stores key-value pairs and allows for fast retrieval of values based on keys.
• HashMap is implemented using an array of linked lists or a balanced tree to handle collisions.

• It uses a hash function to map keys to indices in the array.

• Example: HashMap map = new HashMap<>(); map.put("key", 123); int value = map.get("key");
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Round duration - 45 Minutes
Round difficulty - Medium

It was in the mid day and since I applied for a Frontend role the discussion was majorly around data structure and bit of Javascript.
The interviewer was helping and good listener.

Q1. 
Merge Two Sorted Linked Lists Problem Statement
You are provided with two sorted linked lists. Your task is to merge them into a single sorted linked list and return the head of the combined linked list.
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Q2. 
Sort 0 1 2 Problem Statement
Given an integer array arr of size 'N' containing only 0s, 1s, and 2s, write an algorithm to sort the array.
Input:
The first line contains an integer 'T' representing the n...read more
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Round duration - 60 Minutes
Round difficulty - Medium

It was more of a in depth round on the framework I'm working on and problem solving.

Q1. What is the event loop and what is its significance?
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Q2. Can you provide examples of output-based questions in JavaScript that utilize browser APIs?
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Q3. How would you design a system to support localization in a mobile app?
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Round duration - 75 Minutes
Round difficulty - Hard

It was more of a fitment/managerial round.
Didn't had any coding questions, but was asked more on approaches and optimisations.
Discussions on the project you have worked on.

Q1. You need to find the fastest 3 horses out of a group, given that you can only race 5 horses at a time. How would you approach this problem?
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Q2. How do you debug the root cause of lag on a screen?
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Q3. Can you explain the architecture of the app you have recently worked on?
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