Ola Cabs Software Developer Interview Questions, Process, and Tips

Q1. What is Closure
Ans. 
Closure is a function that captures the environment in which it was created, allowing it to access variables from that environment even after the function has finished executing.
• Closure allows a function to access variables from its outer scope even after the function has finished executing.

• It is created when a function is defined within another function and the inner function references variables from the outer functi...read more
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Q2. Flat nested array
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Q1. Machine coding questions
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Q2. Das based questions
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Q1. Simple questions
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Q2. Simple questions one on one
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One coding and other mcqs on CS concepts

Round duration - 60 minutes
Round difficulty - Medium

This was coding round and was conducted on Google meet with code link shared. Their were 2 interviewers that gave questions and later ran code on sample test cases.

Q1. 
Problem: Permutations of a String
Given a string STR consisting of lowercase English letters, your task is to return all permutations of the given string in lexicographically increasing order.
Explanatio...read more
Ans. Backtracking
The idea is to fix a character at a position and then find the permutations for rest of the characters.
Make a list ‘ans’ which will contain the permutations of the given string.
 
Algorithm:
Let’s define a function generatePermutaionsHelper(Str, l, r). This function generates the permutations of the substring which starts from index  ‘l’ and ends at index  ‘r’.
• Call the function: generatePermutai...read more
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Q2. 
Find the Kth Row of Pascal's Triangle Problem Statement
Given a non-negative integer 'K', determine the Kth row of Pascal’s Triangle.
Example:
Input:
K = 2
Output:
1 1
Input:
K = 4
Output:
1 4 6 ...read more
Ans. Naive Approach
In this approach, we find the row elements of the previous row using recursion, and based on the values of previous row elements, we will evaluate the current row elements.
1. We are given a function kthRow() which takes an integer ‘K’ as the only parameter and returns an integer vector. This is the definition of our recursive function too.
2. As the base condition of our recursive function, we will check if ‘K’ ...read more
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Round duration - 90 minutes
Round difficulty - Medium

This was a Machine Coding Round/LLD round followed by HLD round which was taken by Video Conferencing and Screen Sharing.

Round duration - 60 minutes
Round difficulty - Easy

This was the last round. This was HM round followed by the HR round.

Round duration - 90 minutes
Round difficulty - Medium

It was in the morning, where there were 3 questions to answer.

Q1. 
Number of Islands Problem Statement
You are provided with a 2-dimensional matrix having N rows and M columns, containing only 1s (land) and 0s (water). Your goal is to determine the number of islands in t...read more
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Q2. 
Missing Numbers Problem Statement
You are provided with an array called ARR, consisting of distinct positive integers. Your task is to identify all the numbers that fall within the range of the smallest a...read more
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Q3. 
Count Leaf Nodes in a Binary Tree
Given a binary tree, your task is to count and return the number of leaf nodes present in it.
A binary tree is a data structure where each node has at most two children,...read more
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Round duration - 20 minutes
Round difficulty - Medium

It was a system design round.

Q1. Can you describe the system design of the OLA app?
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Round duration - 45 minutes
Round difficulty - Medium

It was a DS Algo round.

Q1. 
Diagonal Traversal of a Binary Tree Problem Statement
Given a binary tree, your task is to determine the diagonal traversal of the tree.
Example:
Input:
1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1
Output:
...read more
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Q2. 
Minimum Number Of Taps To Water Garden Problem Statement
You are required to determine the minimum number of taps that need to be opened to water an entire one-dimensional garden defined along the x-axis,...read more
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Round duration - 15 minutes
Round difficulty - Medium

HR Round