Flipkart Health+ Web Developer Interview Questions and Answers

Q1. Build an sample app server with express.js
Ans. 
Build a sample app server using express.js
• Install express.js using npm

• Create a new express app

• Set up routes and middleware

• Start the server to listen on a specific port
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Q2. How do you make connection with database in your project
Ans. 
I use JDBC (Java Database Connectivity) to establish connection with the database in my project.
• Use JDBC API to connect to the database

• Load the JDBC driver

• Create a connection object

• Create a statement object

• Execute SQL queries
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Q3. Write multer middleware code.
Ans. 
Multer is a middleware for handling multipart/form-data, used for file uploads in Node.js.
• Install multer package using npm: npm install multer

• Require multer in your Node.js file: const multer = require('multer')

• Set up multer middleware with desired options: const upload = multer({ dest: 'uploads/' })

• Use the upload middleware in your route handler to process file uploads
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2 Graph question of leetcode

Q1. DSA Questions of leetcode
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Q2. DSA Questions
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Q1. Stock buy and sell with at most 2 transaction
Ans. 
Implement a solution to find the maximum profit from buying and selling stocks with at most 2 transactions.
• Use dynamic programming to keep track of maximum profit at each day with 0, 1, or 2 transactions.

• Consider the possibility of splitting the transactions into two separate parts.

• Calculate the maximum profit by iterating through the prices array and updating the maximum profit accordingly.
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Q2. Binary search to find target
Ans. 
Binary search is a divide and conquer algorithm that efficiently finds a target value in a sorted array.
• Divide the array in half and compare the target value with the middle element

• If the target is less than the middle element, search the left half. If greater, search the right half

• Repeat the process until the target is found or the subarray is empty
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Q1. General about project
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Q2. Design paytm wallet
Ans. 
Design a digital wallet system similar to Paytm.
• Allow users to add money to their wallet using various payment methods like credit/debit cards, net banking, UPI, etc.

• Enable users to make payments for various services like mobile recharge, bill payments, online shopping, etc.

• Implement security measures like two-factor authentication, encryption of sensitive data, and regular security audits.

• Provide features like transac...read more
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Q1. About my self and family background
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Q2. About my working experience & work details
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Seat reservation system
bit manipulation
binary tree related

Q1. Bfs / dfs traversal question
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Q1. What is thread ?
Ans. 
A thread is a lightweight process that can run concurrently with other threads within the same process.
• Threads allow for parallel execution of tasks within a single process.

• Threads share the same memory space and resources of the process they belong to.

• Threads can communicate with each other through shared memory or message passing.

• Examples: Java threads, POSIX threads (pthreads) in C/C++.
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Q2. Inter process communication and project?
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Sorting of an array and aptitude

Q1. BFS graph traversal
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Q1. Binary tree question
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Round duration - 60 Minutes
Round difficulty - Medium

It has 3 Coding Questions of medium-hard level and the time limit was 1 hour only. I don’t exactly remember the questions but I was able to do only two of them completely.

Q1. 
Biggest Number Formation Problem
Your task is to construct the largest number possible by concatenating each of the provided positive integers in the array exactly once.
Input:
Integer T denoting the nu...read more
Ans. 
Construct the largest number by concatenating positive integers in the array exactly once.
• Sort the array of integers in a way that the concatenation of the numbers forms the largest possible number.

• Use a custom comparator function to sort the numbers based on their concatenated values.

• Join the sorted array elements to form the final largest number.
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Q2. 
Number of Longest Increasing Subsequence Problem Statement
Given an integer array ARR of length N, determine the count of longest increasing subsequences present in the array.
Explanation:
The Longest I...read more
Ans. 
Count the number of longest increasing subsequences in an integer array.
• Identify the longest increasing subsequences in the array

• Count the number of such subsequences

• Consider the constraints while implementing the solution

• Examples: For input [50, 3, 90, 60, 80], the output is 2
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Round duration - 60 Minutes
Round difficulty - Medium

First, the interviewer introduced himself and then asked to introduce myself. Then he asked about the projects I did. After an introductory discussion on projects, he gave me 3 coding questions on their personal live code environment.

He asked me to explain the approach first and then code it down. I had to explain the time complexity of each solution and optimal code if possible with lesser time complexity.

Q1. 
Cache Operations Problem
You are provided with a cache that can hold a maximum of 'N' elements. Initially, this cache is empty. There are two main operations you can perform on this cache:
Explanation:
...read more
Ans. 
Implement a cache with insert, update, and retrieve operations, returning results of retrieve operations in order.
• Create a cache data structure with specified size 'N'.

• Implement insert and update operations based on the given criteria.

• For retrieve operation, return the value associated with the 'U_ID' if present, else return -1.

• Handle cases where the cache is full and least frequently used items need to be removed.

• Retu...read more
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Q2. 
Possible Words from a Phone Number: Problem Statement
Given a string S composed of digits ranging from 2 to 9, determine all possible strings that can be created by mapping these digits to their correspon...read more
Ans. 
Given a phone number, generate all possible words by mapping digits to letters on a T9 keypad.
• Create a mapping of digits to letters on a T9 keypad

• Use recursion to generate all possible combinations of letters for the given phone number

• Sort the resulting strings in lexicographical order
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Q3. 
Shortest Unique Prefix Problem
You are given an array containing N words. Your task is to derive the shortest prefix for each word that uniquely identifies it amongst the other words. For instance, given t...read more
Ans. 
Given an array of words, find the shortest unique prefix for each word.
• Create a Trie data structure to efficiently store and search for prefixes.

• Traverse the Trie to find the shortest unique prefix for each word.

• Return the list of shortest unique prefixes for all words.
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Round duration - 60 Minutes
Round difficulty - Hard

In this round interviewer gave me 2 coding questions and asked me to code on any editor of my choice. I opened VS code to code those problems.

Q1. 
Maximum Subarray Sum Problem Statement
Given an array arr of length N consisting of integers, find the sum of the subarray (including empty subarray) with the maximum sum among all subarrays.
Explanation...read more
Ans. 
Find the sum of the subarray with the maximum sum among all subarrays in a given array.
• Iterate through the array and keep track of the maximum sum subarray seen so far.

• Use Kadane's algorithm to efficiently find the maximum subarray sum.

• Handle cases where all elements are negative by returning the maximum element in the array.

• Consider the sum of an empty subarray as 0.
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Q2. 
LRU Cache Implementation
Design and implement a data structure for the Least Recently Used (LRU) cache, which supports the following operations:
1. get(key) - Return the value associated with the key if ...read more
Ans. 
Implement a Least Recently Used (LRU) cache data structure with get and put operations.
• Use a combination of a hashmap and a doubly linked list to efficiently implement the LRU cache.

• Keep track of the least recently used item and remove it when the cache reaches its capacity.

• Update the position of an item in the cache whenever it is accessed or updated.

• Ensure constant time complexity for both get and put operations by u...read more
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Round duration - 40 Minutes
Round difficulty - Easy

The interviewer was very friendly. He asked me about myself and previous interviews.