Pine Labs Senior IOS Developer Interview Questions and Answers

This is a HackerEarth coding test that consists of 20 or 22 basic questions focused on iOS and Swift, along with two data structure and algorithm problem-solving questions; one of these is challenging, while the other is easier.

Q1. Basic questions around ios and swift.
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Q2. What is the effective approach to display 'n' number of images in a table view using image URLs?
Ans. 
Use asynchronous image loading to display 'n' images in a table view efficiently.
• Use SDWebImage or AlamofireImage libraries for asynchronous image loading.

• Store image URLs in an array and load images dynamically as cells are displayed.

• Implement caching mechanism to avoid reloading images every time a cell is displayed.
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Round duration - 45 minutes
Round difficulty - Medium

I applied thorough LinkedIn and got a call from HR for the interview.
I went to their Noida Office.
First round was mainly focused on Javascript fundamentals.
Interviewer was also friendly.

Round duration - 1 hour
Round difficulty - Medium

Second round was after 15 minutes of the first round. The focus of this round was DS & Algorithms.

Q1. 
Find Subarray with Given Sum
Given an array ARR of N integers and an integer S, determine if there exists a subarray (of positive length) within the given array such that the sum of its elements equals S....read more
Ans. 
Given an array and a target sum, find a subarray that sums up to the target sum.
• Iterate through the array while keeping track of the running sum and the starting index of the subarray.

• Use a hashmap to store the running sum and its corresponding index.

• If the running sum - target sum is found in the hashmap, it means a subarray with the target sum exists.

• Return the starting and ending indices of the subarray or [-1, -1]
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Q2. 
Minimum Number of Platforms Required
You are provided with two arrays, AT and DT, representing the arrival and departure times of all trains arriving at a railway station.
Your task is to determine the m...read more
Ans. 
This question asks to find the minimum number of platforms required at a railway station so that no train needs to wait.
• Sort the arrival and departure times arrays in ascending order.

• Initialize a variable 'platforms' to 1 and 'maxPlatforms' to 1.

• Iterate through the arrival and departure times arrays simultaneously.

• If the current arrival time is less than or equal to the current departure time, increment 'platforms'.

• If ...read more
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Round duration - 30 minutes
Round difficulty - Easy

Q1. What JavaScript questions did he ask you during the managerial round, and can you describe the work culture of his team?
Ans. 
The interviewer asked about JavaScript questions and the work culture of the team during the managerial round.
• JavaScript questions related to closures, prototypes, event handling, and asynchronous programming may have been asked.

• Work culture may involve collaboration, innovation, agile methodologies, and continuous learning.

• Examples of work culture could include regular team meetings, code reviews, hackathons, and ment
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Round duration - 15 minutes
Round difficulty - Easy

It was a hacker earth test. The questions i had got was weird and the answer was something along the lines of if(num==2) return "y" else return "N"

Q1. Usual leetcode questions
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Q1. Twitter system design
Ans. 
Twitter is a social media platform that allows users to share short messages called tweets.
• Twitter uses a distributed system architecture to handle high traffic and ensure scalability.

• The system consists of multiple servers for different functions such as user authentication, tweet storage, and search indexing.

• Twitter also uses caching and load balancing techniques to improve performance.

• To handle real-time updates, Tw...read more
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Q2. Api design with filters
Ans. 
API design with filters allows users to retrieve specific data by applying filters to the API request.
• Filters can be applied to different fields in the API request, such as date range, location, or category.

• API design should include clear documentation on available filters and their syntax.

• Filters can be combined to create more complex queries.

• Examples of filter syntax include using operators such as '>', '<', '>=', '<...read more
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Round duration - 90 minutes
Round difficulty - Medium

Started with projects discussion and internships and moved forward with coding problems.
It started at around 6:00 PM and lasted for 90 minutes approximately
The interviewer was very cool, he even gave me some tips on improving myself further at the end of the interview.

Q1. 
Longest Substring with At Most K Distinct Characters
Given a string S of length N and an integer K, find the length of the longest substring that contains at most K distinct characters.
Input:
The first...read more
Ans. 
Find the length of the longest substring with at most K distinct characters in a given string.
• Use a sliding window approach to keep track of the characters and their counts within the window.

• Maintain a hashmap to store the characters and their frequencies.

• Update the window size and characters count as you iterate through the string.

• Return the maximum window size encountered for each test case.
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Q2. 
Maximum Frequency Number Problem Statement
Given an array of integers with numbers in random order, write a program to find and return the number which appears the most frequently in the array.
If multip...read more
Ans. 
Find the number with the maximum frequency in an array of integers.
• Iterate through the array and keep track of the frequency of each number using a hashmap.

• Find the number with the maximum frequency and return it.

• If multiple elements have the same maximum frequency, return the one that appears first.
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Q3. 
Ninja and Bombs Problem Statement
Ninja wants to travel from his house to his best friend's house. The locations of the houses are on a 2D coordinate plane, where Ninja's house is located at the origin (0...read more
Ans. 
Determine if Ninja can reach his friend's house with even x-coordinate without using modulus operator.
• Check if the x-coordinate is even or odd by using bitwise AND operation with 1.

• Return 1 if x-coordinate is even, else return 0.

• Handle multiple test cases by iterating through each input.
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Round duration - 60 minutes
Round difficulty - Easy

I was asked a coding question then, a system design question and some basic operating systems and oops questions

Q1. 
Find Duplicates in an Array
Given an array ARR of size 'N', where each integer is in the range from 0 to N - 1, identify all elements that appear more than once.
Return the duplicate elements in any orde...read more
Ans. 
Find duplicates in an array of integers within a specified range.
• Iterate through the array and keep track of the count of each element using a hashmap.

• Return elements with count greater than 1 as duplicates.

• Time complexity can be optimized to O(N) using a set to store seen elements.
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Q2. Can you design a Google Search Engine?
Ans. 
Designing a Google Search Engine involves creating a web crawler, indexing system, and ranking algorithm.
• Develop a web crawler to discover and retrieve web pages.

• Implement an indexing system to store and organize the content of web pages.

• Design a ranking algorithm to determine the relevance of search results.

• Include features like autocomplete, spell check, and personalized search results.

• Optimize for speed and scalabil...read more
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