OLX Security Engineer Interview Questions and Answers

Round duration - 60 Minutes
Round difficulty - Easy

Q1. 
Find the k-th Node from the End of a Linked List
Given the head node of a singly linked list and an integer 'k', this problem requires you to determine the value at the k-th node from the end of the linke...read more
Ans. 
To find the k-th node from the end of a linked list, iterate through the list to determine the size, then traverse again to reach the k-th node from the end.
• Iterate through the linked list to determine its size.

• Calculate the position of the k-th node from the end based on the size of the list.

• Traverse the list again to reach the k-th node from the end.

• Return a pointer to the k-th node from the end.
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Round duration - 60 Minutes
Round difficulty - Easy

High level System Design

Q1. Can you design a system like Uber, explaining the various components and architecture involved?
Ans. 
Designing a system like Uber involves components like user app, driver app, server, database, and algorithms for matching and routing.
• User app for booking rides and tracking

• Driver app for accepting rides and navigation

• Server for handling requests and communication between apps

• Database for storing user, driver, and ride information

• Algorithms for matching riders with drivers and routing
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Round duration - 45 minutes
Round difficulty - Easy

Basic HR questions

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 Problem Statement
Given an array of distinct positive integers and a number 'K', your task is to find the K'th largest element in the array.
Example:
Input:
Array: [2,1,5,6,3,8], K ...read more
Ans. 
Find the Kth largest element in an array of distinct positive integers.
• Sort the array in non-increasing order

• Return the Kth element from the sorted array

• Handle multiple test cases
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Q2. 
Orange Rotting Problem Statement
Consider a grid containing oranges. Each cell in this grid can hold one of three integer values:
• Value 0: Represents an empty cell.
• Value 1: Represents a fresh orang...read more
Ans. 
The task is to determine the minimum time required for all fresh oranges to become rotten in a grid.
• Create a queue to store the rotten oranges and their time of rotting.

• Iterate through the grid to find the initial rotten oranges and add them to the queue.

• Perform BFS by popping each rotten orange from the queue, rot adjacent fresh oranges, and add them to the queue with updated time.

• Continue until the queue is empty, ke...read more
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Round duration - 45 minutes
Round difficulty - Easy

This was a design round.