Amazon L4 Engineer Interview Questions and Answers

Q1. Data structure and algorithm
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Q2. Some tricky logical question
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Q3. Stack and queue
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Q4. Some basic question about system Design
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Hackerrank Coding Test, Leetcode medium questions

HLD test, was asked to design an online coding platform like leetcode

Q1. Most interesting project you have worked on
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Q2. How do you handle conflict at workplace
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Some database questions,some java questions .

Q1. What is the difference between javascript and jQuery.
Ans. 
JavaScript is a programming language used for web development, while jQuery is a library built with JavaScript to simplify HTML document traversal and manipulation.
• JavaScript is a programming language, while jQuery is a library written in JavaScript.

• JavaScript can be used for a wide range of tasks, while jQuery is mainly used for DOM manipulation and event handling.

• JavaScript is a core technology for web development, w...read more
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Q2. Define different types of join
Ans. 
Different types of joins are used in SQL to combine rows from two or more tables based on a related column between them.
• Inner Join: Returns rows when there is at least one match in both tables.

• Left Join (or Left Outer Join): Returns all rows from the left table and the matched rows from the right table.

• Right Join (or Right Outer Join): Returns all rows from the right table and the matched rows from the left table.

• Full ...read more
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Q3. Define multithreading concept and exception handling.
Ans. 
Multithreading allows multiple threads to run concurrently, while exception handling deals with errors in a program.
• Multithreading involves running multiple threads simultaneously to improve performance and responsiveness.

• Threads share the same memory space but have their own program counter and registers.

• Exception handling is a mechanism to handle errors or exceptional situations in a program.

• It helps prevent the prog...read more
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Q1. What is distributed system
Ans. 
A distributed system is a collection of independent computers that appear to the users as a single coherent system.
• Consists of multiple computers connected through a network

• Allows for parallel processing and fault tolerance

• Examples include cloud computing, peer-to-peer networks, and distributed databases
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Q2. Jenkins to deploy the automation from git repo, procedure
Ans. 
Use Jenkins pipeline to deploy automation from git repo
• Create a Jenkins pipeline job

• Configure the job to pull code from the git repository

• Define the deployment steps in the Jenkinsfile

• Use Jenkins plugins like Git plugin and Pipeline plugin for automation

• Ensure proper permissions and credentials are set up for accessing the git repo
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React based
problem solving round

Q1. Given array of integer create subarray with sum = 0
Ans. 
Create subarrays with sum = 0 from given array of integers.
• Iterate through the array and keep track of the running sum.

• Store the running sum in a hashmap and check if the current sum - any previous sum equals 0.

• If yes, then the subarray between those two indices has a sum of 0.
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Q2. Left view of binary tree
Ans. 
The left view of a binary tree is the set of nodes visible when the tree is viewed from the left side.
• Traverse the tree in a level order manner and keep track of the first node at each level.

• Use a queue to store nodes at each level and update the left view nodes accordingly.

• Example: For a binary tree with root node 1, left child 2, and right child 3, the left view would be [1, 2].
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45 min round. Similar to Leetcode medium level question.

45 min coding round, 2 question asked

Q1. System design of proximity service
Ans. 
Design a system for proximity service
• Utilize geolocation data to track user locations

• Implement algorithms to calculate proximity between users

• Use real-time updates to notify users of nearby contacts
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Q1. Behavioral questions
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Implement an iterator to flatten 2D vector

Q1. Find shortest path to get all keys
Ans. 
Use Dijkstra's algorithm to find the shortest path to get all keys
• Implement Dijkstra's algorithm to find the shortest path in a graph

• Consider the keys as nodes in the graph and the paths between keys as edges

• Keep track of the keys collected and update the shortest path accordingly
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