Ola Cabs Software Developer Intern Interview Questions and Answers

More focus on dp,graphs.

Q1. Focus on backend concepts,routing.
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Q2. Question on flood fill algo,backtracking.
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Round duration - 65 minutes
Round difficulty - Hard

Timing (6pm - 8pm)
Environment was user friendly
As usual the online round had three coding questions and 20 MCQs. This was a pretty easy round and it’s duration was 65 minutes. The round consisted of questions from various domains like Algorithm, Data Structure, Operating System and Aptitude.

Q1. 
Determine Count of Good Triplets
You are given two arrays ARR1 and ARR2, containing N and M elements respectively. There are two types of 'good triplets' that need to be identified in these arrays.
Type ...read more
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Q2. 
Split the String Problem Statement
You are given a string str consisting of N lowercase alphabets. Your task is to determine if it is possible to divide the string into three non-empty substrings such tha...read more
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Round duration - 40 minutes
Round difficulty - Medium

Q1. 
Check if Two Trees are Mirror
Given two arbitrary binary trees, your task is to determine whether these two trees are mirrors of each other.
Explanation:
Two trees are considered mirror of each other if...read more
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Q2. 
Snake and Ladder Problem Statement
Given a 'Snake and Ladder' board with N rows and N columns, where positions are numbered from 1 to (N*N) starting from the bottom left, alternating direction each row, f...read more
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Round duration - 90 minutes
Round difficulty - Easy

This round had 2 coding problems and we had to code it on hackerearth only.
The use of Outside IDE was forbidden.
The timing of test was 12:00 PM to 1:30 PM.

Q1. 
Meeting Rescheduling Challenge
Ninja is tasked with organizing a meeting in an office that starts at time ‘0’ and ends at time ‘LAST’. There are ‘N’ presentations scheduled with given start and end times....read more
Ans. Brute Force Approach
Algorithm:
 
• The idea here is to find the maximum sum subarray of size ‘K+1’, where the array will contain empty slots.
• First, we create an array named emptySlots[], to store the time duration in which there is no presentation.
• Run a loop to traverse all presentations, and in each iteration, add START[i] - END[i-1] (which gives a free slot between the ith presentation) into the array emptySlots[].
• N...read more
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Q2. 
Total Unique Paths Problem Statement
You are located at point ‘A’, the top-left corner of an M x N matrix, and your target is point ‘B’, the bottom-right corner of the same matrix. Your task is to calcula...read more
Ans. Recursive Approach
We can easily count the total number of paths by making a recursive algorithm.
 
The steps are as follows:
 
1. We are given a function UNIQUEPATHS(), which takes two integers ‘M’ and ‘N’ as parameters and returns a single integer. This will be the definition of our recursive function too.
2. As our base condition, we will check if our number of rows (‘M’) or a number of columns (‘N’) is equal to 1. If...read more
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Round duration - 90 minutes
Round difficulty - Medium

This round was coding round with discussion .
The interviewer tried to trick the questions and wanted to test how we respond if something is asked out of preparation.
The code we ran on Google Docs was checked on Online IDE if it ran for sample inputs.
Timing : 12:00 PM to 1:30 PM

Q1. 
Minimum Operations to Connect a Graph
You are given a graph with 'N' vertices labeled from 1 to 'N' and 'M' edges. In one operation, you can shift an edge from being between two directly connected vertice...read more
Ans. Breadth First Search.
For a graph with ‘N’ vertices to be connected, there must be at least ‘N’ - 1 edges in the graph. If a graph has less than ‘N' - 1 edges it is impossible to make the graph connected. Otherwise, it is always possible to make graph connected. As we need to find the minimum number of operations to make the graph connected we will think greedily. We will find the total number of connected components in...read more
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Q2. 
Snake and Ladder Problem Statement
Given a 'Snake and Ladder' board with N rows and N columns, where positions are numbered from 1 to (N*N) starting from the bottom left, alternating direction each row, f...read more
Ans. BFS
We will use Breadth-First Search to find the shortest path from cellNumber 1 to cellNumber N*N.
1. We will maintain a queue of cellNumber where the front of the queue will always contain a cell which can be reached by minimum dice throw from starting cell (cellNumber = 1).
2. Create a minDiceThrow array of size N*N initialise it with the maximum value (INT_MAX)
3. Start with pushing cellNumber 1 and updating minDiceThrow[1] = 0...read more
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Round duration - 75 minutes
Round difficulty - Hard

This was a problem solving round and lasted for 75 minutes. The interviewer gave me a very complicated question.
The round was held on Google Meet and I was supposed to tell him the approach and write code on shared Google Docs.

Q1. 
XOR Query Problem Statement
Assume you initially have an empty array called ARR. You are required to return the updated array after executing Q number of queries on this array.
There are two types of que...read more
Ans. Brute Force
Approach:
• It is a brute force approach where we will create an empty array initially of size 10^5 + 1.
• Now, whenever we have a query of type 1 we will insert the value of VAL in the array. And when the query of type 2 comes then we will iterate through our array and perform an XOR operation with VAL to every value present in our array.
• Finally, we will return our array.
 
Algorithm:
• Create an array ans.
• Now it...read more
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