Uber SDE-2 Interview Questions, Process, and Tips

Q1. Data structure related question
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Q1. Nodejs related questions
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Q2. Promises Async Await Events emitter
Ans. 
Promises, async/await, and event emitters are all ways to handle asynchronous operations in JavaScript.
• Promises provide a way to handle asynchronous operations by returning a promise object that can be resolved or rejected.

• Async/await is a syntax for working with promises that makes code easier to read and write.

• Event emitters allow you to create custom events that can be triggered and listened for in your code.
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Q1. System design related question
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Q2. Design a system like facebook
Ans. 
Design a system like Facebook
• Create a user registration and login system

• Implement a news feed for users to see updates from friends

• Allow users to create and join groups

• Include features like messaging, commenting, and liking posts

• Implement privacy settings for users to control who can see their content
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Q1. System design and behavioral
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Round duration - 60 minutes
Round difficulty - Easy

The first round was a coding round. 2 DSA based questions were asked.

Q1. 
Maximum Meetings Problem Statement
Given the schedule of N meetings with their start time Start[i] and end time End[i], you need to determine which meetings can be organized in a single meeting room such ...read more
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Q2. 
Peak Element Finder
For a given array of integers arr, identify the peak element. A peak element is an element that is greater than its neighboring elements. Specifically, if arr[i] is the peak, then both...read more
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Round duration - 45 minutes
Round difficulty - Medium

The second round was a system design round.

Round duration - 30 minutes
Round difficulty - Easy

This was a typical managerial round.

Amazon Online assessment which consisted of 2 coding DSA medium question

Q1. Question related to TreeMap
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Q2. Question related BFS
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Q3. System Design - Design Feed system
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Diameter of a binary tree and bfs and dfs questions

Data structure and algorithms

Q1. System design questions
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Q1. Behavioural questions related to leadership principle.
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Round duration - 60 Minutes
Round difficulty - Medium

Timing: 10AM-11AM
Interviewer was quite supportive and helpful.
Environment was normal as usual and it was morning time

Round duration - 60 Minutes
Round difficulty - Medium

Timing: 11AM-12PM
The interviewer was SDE2
He was checking the code for edge cases and was hinting if required

Q1. 
Implementing a Priority Queue Using Heap
Ninja has been tasked with implementing a priority queue using a heap data structure. However, he is currently busy preparing for a tournament and has requested yo...read more
Ans. Array representation of heap
 
1. Since the heap is maintained in the form of a complete binary tree, the heap can be easily represented in the form of an array.
2. To keep the tree complete and shallow, while inserting a new element insert it in the leftmost vacant position in the last level i.e., at the end of our array, and perform some operation to maintain the property of the heap.
3. Similarly, for deleting the maximum e...read more
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Q2. 
Ninja and the Bulbs Challenge
Ninja owns an electronic shop and possesses 'N' bulbs. To verify the quality of the bulbs, Ninja performs a unique technique. After 'N' rounds of this process, bulbs that rem...read more
Ans.  Brute Force
Approach:
A brute force solution to this problem is to turn on and off the bulbs N time, then at last check the number of bulbs that are on.

 
Algorithm:
• Take a boolean array of ‘BULBS’ of size N+1.
• Itertate on ‘i’ from 1 to ‘N’
  • Iterate on ‘j’ form ‘i’ to ‘N’ and each time increment ‘j’ as ‘j’ += ‘i’.
    • if(BULBS[j] == true) then make it false.
    • If (BULBS[j]==false) then make it true.
• Intialise a variable ‘COUNT’ =...read more
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Round duration - 60 Minutes
Round difficulty - Medium

Timing: 6PM-7PM
The interviewer was not interactive and didn't gave any feedback whatsoever.
It was Hiring Manager Round
Interviewer was Software Development Manager at Amazon

Q1. 
Maximize the Sum Through Two Arrays
You are given two sorted arrays of distinct integers, ARR1 and ARR2. If there is a common element in both arrays, you can switch from one array to the other.
Your task...read more
Ans. Recursive
In this problem, our primary focus is on the common elements i.e. an element that is present in both the arrays. Then, we have to decide whether we have to make a switch. So for that, first we store all the elements of ‘ARR1’ and ‘ARR2’ into ‘MAP1’ and ‘MAP2’ respectively. 
 
Now we call our ‘maximiseSumHelper’ function. We call this function for both cases i.e starting with ‘ARR1’ and starting with ‘A...read more
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Round duration - 60 minutes
Round difficulty - Easy

Started with brief intro(5 mins) about interviewer.
Problem solving question, question was already there in the codelink shared by the interviewer. He explained the problem again with sample testcase. 
The Interviewer was friendly.

Q1. 
Course Schedule II Problem Statement
You are provided with a number of courses 'N', some of which have prerequisites. There is a matrix named 'PREREQUISITES' of size 'M' x 2. This matrix indicates that fo...read more
Ans. Breadth-First Search
Our current algorithm is based on the idea of the BFS approach. We first process all the courses with 0 in-degree implying no prerequisite courses required. If we remove all these courses from the graph, along with their outgoing edges, we can find out the courses/nodes that should be processed next. These would again be the nodes with 0 in-degree. We can continuously do this until all the courses h...read more
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Q2. Design a live video broadcast platform.
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Round duration - 90 minutes
Round difficulty - Medium

There were 2 interviewers(India HM and Seattle HM), India HM was just shadowing and didn't ask any questions. Started with intro, he asked in detail about what I do at current company(10 mins). Again, jumped into LP's(25 mins).

Q1. 
Distance Between Two Nodes in a Binary Tree
Given a binary tree and the values of two distinct nodes, determine the distance between these two nodes in the tree. The distance is defined as the minimum num...read more
Ans. Naive Approach
In any rooted tree, the distance between two nodes 'U' and 'V' can be found by finding the lowest common ancestor (LCA), ‘x’ of two nodes. The lowest common ancestor (LCA) between nodes 'U' and 'V' is defined as the lowest node in the tree that has both 'U' and 'V' as descendants, where we define each node to be a descendant of itself (so if 'U' has a direct connection from 'V', 'V' is the lowest common a...read more
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Q2. 
Median in a Stream Problem Statement
Your task is to determine the median of integers as they are read from a data stream. The median is the middle value in the ordered list of numbers. If the list length...read more
Ans. Brute force approach
Store the incoming data elements in a vector. Sort the vector everytime you need to output the median.
Algorithm:
1. Store the incoming elements of the data stream in a vector.
2. Step by step insert one element and sort the vector as soon as any element is added in the vector.
3. If the size of the vector is odd, print the middle element of the sorted vector.
   If the size of the vector is even, return the mean of...read more
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Round duration - 60 minutes
Round difficulty - Medium

There was only 1 interviewer in this round and We had no video sharing in this round so it was becoming difficult to understand each other.