Uber Software Engineer Interview Questions, Process, and Tips

Round duration - 60 Minutes
Round difficulty - Easy

Q1. K-th node from the end of the linked list
Given the head node of the singly linked list and an integer ‘k’, , find the value at the kth node from the end of the linked list.
For example:
For the above-...read more
Ans. 
Explained the approach by using 2 traversals - First to find the length of list and then to delete the node.

Also, discussed an approach to do it in one traversal.
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Round duration - 60 Minutes
Round difficulty - Easy

High level System Design

Q1. System Design Question
Design Uber
Ans. 
Tip 1 : Study system design in depth
Tip 2 : Be familiar how to scale your design
Tip 3 : Be familiar with concepts like single point of failure
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Round duration - 45 minutes
Round difficulty - Easy

Basic HR questions

Q1. Basic HR questions
Why you want to join Uber
What are your expectations from Uber
Ans. 
Tip 1 : Show the HR that you are really interested in Uber
Tip 2 : Study about the company
Tip 3 : Try to negotiate
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Round duration - 120 minutes
Round difficulty - Easy

It was a mix of mathematical aptitude, logical ability, and puzzles along with 2 programming questions of easy and medium levels. Time was enough and no sectional time was present. 1-2 MCQs on SQL was also present.

Q1. Boolean Matrix
Given a 2-dimensional boolean matrix mat of size N x M, modify the matrix such that if an element is 1, set its entire row and column to 1 i.e. if mat[i][j] = 1, then make all the elements o...read more
Ans. 
You need to make the modifications in the input matrix.
You do not need to print anything, it has already been taken care of.
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Round duration - 60 minutes
Round difficulty - Easy

It was an online video interview round on HackerEarth with a simultaneous code option. It was mostly justifying your resume in the first 15 minutes. After that OOPS was majorly asked. Basics of programming including questions on STL were asked. A class that required inheritance was asked by the interviewer to write. I was helped by the interviewer if I got stuck somewhere, Some questions on the implementation of hashmaps and priority queues were also asked. A puzzle was asked which luckily struct to me at that moment.

Q1. Connect n ropes with minimum cost
You have been given 'N' ropes of different lengths, we need to connect these ropes into one rope. The cost to connect two ropes is equal to sum of their lengths. We need to...read more
Ans. 
Input format :
The first line of input contains an integer value 'N'. It denotes the total number of ropes.

The second line of input contains 'N' single space-separated integers representing the length of each rope i.e. a1, a2, a3, ... an.
Output Format :
The only line of output will contain an integer, the minimum cost for connecting all the ropes.
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Round duration - 60 minutes
Round difficulty - Medium

It started with an informal talk after he gave his introduction. We talked about the cyclone that was going to be there and what I did in my internship and my previous projects. Then we moved to questions. After solving both questions he asked if I had questions.

Q1. Kth Largest Element in an Array
You are given an array consisting of 'N' distinct positive integers and a number 'K'. Your task is to find the kth largest element in the array.
Example:
C...read more
Ans. 
To solve the question using a max heap, make a max heap of all the elements of the list. Run a loop for k-1 times and remove the top element of the heap. After running the loop, the element at top will be the kth largest element, return that. Time Complexity : O(n + klogn)

The question can also be solved using a min heap. 
 
Approach :
 
1. Create a min heap class with a capacity of k
 
2. When the heap re...read more
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Q2. Minimum time required to rot all oranges
You have been given a grid containing some oranges. Each cell of this grid has one of the three integers values:
Value 0 - representing an empty cell.
Value...read more
Ans. 
BFS can be used here. 
Algorithm : 

1. Create an empty queue Q. 
 
2. Find all rotten oranges and enqueue them to Q. Also, enqueue a delimiter to indicate the beginning of the next time frame.
 
3. Run a loop While Q is not empty
 
4. Do following while delimiter in Q is not reached
4.1. Dequeue an orange from the queue, rot all adjacent oranges. While rotting the adjacent, make sure that the time ...read more
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Round duration - 45 minutes
Round difficulty - Easy

This was a design round.

Q1. System Design Question
How to stream an image such that all clients see the same image at the same time? You need to take care of delays, network problems. He kept on adding new elements like compression, s...read more
Ans. 
Tip 1 : Firstly, remember that the system design round is extremely open-ended and there’s no such thing as a standard answer. Even for the same question, you’ll have a totally different discussion with different interviewers.

Tip 2 : Before you jump into the solution always clarify all the assumptions you’re making at the beginning of the interview. Ask questions to identify the scope of the system. This will clear the...read more
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