Uber Senior Production Engineer Interview Questions and Answers

Q1. What is actual rule is using to sale more products in this company
Ans. 
The actual rule for selling more products in this company is to focus on customer needs and provide excellent customer service.
• Focus on customer needs and preferences

• Provide excellent customer service

• Offer promotions and discounts

• Maintain high product quality

• Stay up-to-date with market trends

• Build strong relationships with customers

• Encourage customer feedback and use it to improve

• Train sales staff to be knowledgeable a
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Round duration - 90 minutes
Round difficulty - Medium

Online test which can be attempted anytime between 22 May 2020, 06:00 AM and 25 May 2020, 01:00 AM

Q1. 
Postfix Expression Evaluation Problem Statement
Given a postfix expression, your task is to evaluate the expression. The operator will appear in the expression after the operands. The output for each expr...read more
Ans. 
Evaluate postfix expressions by applying operators to operands in a given order.
• Iterate through the postfix expression and push operands onto a stack

• When an operator is encountered, pop the required number of operands from the stack, apply the operator, and push the result back onto the stack

• Continue until the entire expression is evaluated and the final result is left on the stack
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Q2. 
Dice Throws Problem Statement
You are given D dice, each having F faces numbered from 1 to F. The task is to determine the number of possible ways to roll all the dice such that the sum of the face-up num...read more
Ans. 
The task is to determine the number of possible ways to roll all the dice such that the sum of the face-up numbers equals the given 'target' sum.
• Use dynamic programming to solve the problem efficiently.

• Create a 2D array to store the number of ways to achieve each sum with different number of dice.

• Iterate through the dice and sum possibilities to fill up the array.

• Return the result modulo 10^9 + 7.

• Optimize the solution ...read more
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Round duration - 60 minutes
Round difficulty - Medium

June 25 2020
Timing: 12:00 pm to 1:00 pm
This round was completely devoted to coding. I was asked to introduce myself and then 2 coding questions were asked.

Q1. 
Find First and Last Positions of an Element in a Sorted Array
Given a sorted array ARR consisting of N integers and an integer X, find the first and last positions of occurrence of X in the array.
Note:
...read more
Ans. 
Find the first and last positions of an element in a sorted array efficiently.
• Use binary search to find the first occurrence of X in the array.

• Use binary search to find the last occurrence of X in the array.

• Handle cases where X is not present or present only once.

• Return the first and last positions as 0-based indices.
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Q2. 
Maze with N Doors and 1 Key Problem Statement
You are given an N x N maze where some cells have doors, and you have a key that can be used only once to open a door. Determine if there exists a path from t...read more
Ans. 
Determine if there exists a path from the top-left cell to the bottom-right cell of a maze with N doors and 1 key.
• Use depth-first search (DFS) or breadth-first search (BFS) to explore possible paths through the maze.

• Keep track of the cells visited and use the key only once to open doors.

• Check if the bottom-right cell is reachable after traversing the maze.

• Handle edge cases such as the top-left and bottom-right cells ha...read more
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Round duration - 60 minutes
Round difficulty - Medium

9th July 2020
6:30PM to 7:30PM

Round duration - 60 minutes
Round difficulty - Easy

23-July 2020
4:00 PM to 5:00 PM
Coding questions + Several questions on computer fundamentals and networking were asked in a rapid-fire manner.

Q1. 
Stock Trading Maximum Profit Problem
Given the stock prices for 'N' days, your goal is to determine the maximum profit that can be achieved. You can buy and sell the stocks any number of times but can onl...read more
Ans. 
The goal is to determine the maximum profit that can be achieved by buying and selling stocks on different days.
• Iterate through the stock prices and buy on the days when the price is lower than the next day's price, and sell on the days when the price is higher than the next day's price.

• Calculate the profit by summing up the differences between buying and selling prices.

• Repeat the process for each test case and output
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Round duration - 60 minutes
Round difficulty - Medium

6- Aug 2020
3:00 PM to 4:00 PM
Resceduled to: @5:30 PM
Projects, Fundamentals check, Behavioral, Coding

Q1. 
Path Counting in Directed Graph
Given a directed graph with a specified number of vertices V and edges E, your task is to calculate the total number of distinct paths from a given source node S to all ot...read more
Ans. 
Calculate total number of distinct paths from a given source node to all other nodes in a directed graph.
• Use dynamic programming to keep track of the number of paths from the source node to each node.

• Consider the modulo operation to handle large numbers efficiently.

• Start by initializing the number of paths from the source node to itself as 1.

• Iterate through all edges and update the number of paths for each destination ...read more
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Round duration - 90 Minutes
Round difficulty - Easy

Two coding questions were asked and 90 minutes of time was allotted to solve both the problems

Q1. 
Find All Pairs Adding Up to Target
Given an array of integers ARR of length N and an integer Target, your task is to return all pairs of elements such that they add up to the Target.
Input:
The first line ...read more
Ans. 
Given an array of integers and a target, find all pairs of elements that add up to the target.
• Iterate through the array and for each element, check if the target minus the element exists in a hash set.

• If it exists, add the pair to the result. If not, add the element to the hash set.

• Handle cases where the same element is used twice to form a pair.

• Return (-1, -1) if no pair is found.
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Q2. 
Shortest Path in a Binary Matrix Problem Statement
Given a binary matrix of size N * M where each element is either 0 or 1, find the shortest path from a source cell to a destination cell, consisting only...read more
Ans. 
Find the shortest path in a binary matrix from a source cell to a destination cell consisting only of 1s.
• Use Breadth First Search (BFS) algorithm to find the shortest path in the binary matrix.

• Keep track of visited cells to avoid revisiting them.

• Update the path length as you traverse the matrix.

• Return -1 if no valid path exists from source to destination.
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Round duration - 60 Minutes
Round difficulty - Medium

The duration was approx 1 hour. The interview was taken by a young SDE-2.

Q1. 
Character Frequency Problem Statement
You are given a string 'S' of length 'N'. Your task is to find the frequency of each character from 'a' to 'z' in the string.
Example:
Input:
S : abcdg
Output:
1...read more
Ans. 
The task is to find the frequency of each character from 'a' to 'z' in a given string.
• Create an array of size 26 to store the frequency of each character from 'a' to 'z'.

• Iterate through the string and increment the count of the corresponding character in the array.

• Print the array of frequencies as the output.
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Q2. 
Fire in the Cells Problem Statement
Given a matrix MAT of size N * M, where each cell is either on fire or safe, determine if a person can reach an escape cell without being burnt. The person starts from ...read more
Ans. 
Determine if a person can reach an escape cell without encountering fire in a matrix.
• Check if the person can reach an escape cell without encountering fire by simulating the movement of the person and fire spread.

• If the person can reach an escape cell, return the time taken; otherwise, return -1.

• Consider the constraints and edge cases while implementing the solution.
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Round duration - 60 Minutes
Round difficulty - Hard

The interviewer introduced himself and asked me to introduce myself.
I told him about the different projects that I had done and the work in the previous company.
I had worked on AWS(Amazon Web Services) so he asked me all the AWS services that I had worked with and to explain one of them. 
I explained about the working of ECS(Elastic Container Service).
After this, he moved to the coding questions.

Q1. 
Maximum 0-1 Distance Problem Statement
Given a binary matrix of size N*M, find the maximum distance 'di' for every 0-cell to its nearest 1-cell, where the distance is measured using Manhattan distance. Th...read more
Ans. 
Find the maximum Manhattan distance from a 0-cell to its nearest 1-cell in a binary matrix.
• Iterate through the matrix to find all 0-cells and calculate their distances to nearest 1-cells using Manhattan distance formula

• Keep track of the maximum distance found so far and update it if a larger distance is encountered

• Return the maximum distance as the final result
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Q2. 
Search for Indices with Given Difference and Distance
You are provided with an array containing 'N' non-negative integers, along with two other non-negative integers 'K' and 'M'. Your task is to identify ...read more
Ans. 
Find a pair of indices in an array with given difference and distance constraints.
• Iterate through the array and check all possible pairs of indices to satisfy the conditions

• Use nested loops to compare each pair of indices and their corresponding elements

• Return 'valid' if a pair of indices is found that meets the conditions, otherwise return 'invalid'
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Round duration - 60 Minutes
Round difficulty - Medium

The interviewer was a very senior person with at least 10-15 years of experience. He introduced himself and asked me to tell him about myself. (Leadership principle questions followed)
 

Q1. 
Special Binary Tree Problem Statement
Determine whether an arbitrary binary tree is special. A binary tree is called special if every node in this tree has either zero or two children.
Example:
Input:
...read more
Ans. 
Determine if a binary tree is special if every node has zero or two children.
• Traverse the tree and check if each node has either 0 or 2 children.

• Use a recursive approach to check children of each node.

• If any node has only one child, return false immediately.

• Example: For the given input, the output should be true.
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Round duration - 60 Minutes
Round difficulty - Medium

The interview started with introductions and some Leadership principle questions. The interviewer was again a senior person with at least 10-15 years of experience.

I was asked to explain some AWS services.
He asked me to tell about a time when I had a tight deadline and how I worked during it.
He asked me about a time when I took initiative and came up with something new which helped the entire team.
I had prepared well for the LP questions and was able to answer everything.
After this, we move on to coding questions.

Q1. 
Word Presence in Sentence
Determine if a given word 'W' is present in the sentence 'S' as a complete word. The word should not merely be a substring of another word.
Input:
The first line contains an in...read more
Ans. 
Check if a given word is present in a sentence as a complete word.
• Split the sentence into words using spaces as delimiter.

• Check if the given word matches any of the words in the sentence.

• Ensure that the word is not just a substring of another word in the sentence.
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Q2. 
LRU Cache Design Question
Design a data structure for a Least Recently Used (LRU) cache that supports the following operations:
1. get(key) - Return the value of the key if it exists in the cache; otherw...read more
Ans. 
Design a Least Recently Used (LRU) cache data structure that supports get and put operations with capacity constraint.
• Use a combination of hashmap and doubly linked list to implement the LRU cache.

• Keep track of the least recently used item and update it accordingly.

• Ensure to handle cache capacity by evicting the least recently used item when the cache is full.
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