Chetu Java Full Stack Developer Interview Questions and Answers

Q1. Very basic top 50 questions on internet, basic java, inheritance, oops, solid, collections
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Q2. Diff between abstract and interface, method overloading, overriding, microservices, how do microservice communicate
Ans. 
Abstract class is a class that cannot be instantiated, while an interface is a blueprint of a class with only abstract methods.
• Abstract class cannot be instantiated, but can have both abstract and non-abstract methods.

• Interface can only have abstract methods and cannot have method implementations.

• Method overloading is having multiple methods in the same class with the same name but different parameters.

• Method overridin...read more
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Q3. Spring boot annotations, DI, hibernate, bean scopes
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Q4. Fibonacci series print
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Q1. Singliton class
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Q2. Immutable class
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Q3. Most occured letter in string ? Problem to code
Ans. 
Find the most occurred letter in a given string.
• Iterate through the string and count the occurrences of each letter

• Store the counts in a map or array

• Find the letter with the highest count
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Q4. Global exception handler ?
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Q5. Design principle?
Ans. 
Design principle is a set of guidelines that help software developers create maintainable and scalable code.
• Design principles help in creating code that is easy to understand, modify, and maintain.

• Examples of design principles include SOLID principles, DRY (Don't Repeat Yourself), KISS (Keep It Simple, Stupid), and YAGNI (You Aren't Gonna Need It).
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Q1. Design patterns
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Q2. OOPS Concept
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Q1. Questions from JavaScript, React and Node. 1st round. 2 coding questions on String and Array. Questions on Past employment experiece.
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Q1. Event Loop, SQL queries. 2 coding questions on Array and Strings.
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Q2. JavaScript and Node questions
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Q1. Why Oracle Cerner etc....
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Q1. Project, Oops Concept, Java , which technology u have used ? Framework
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Q2. Framework, Explain Long Polling ,
Ans. 
Long polling is a web technique where the client sends a request to the server and the server holds the connection open until new data is available.
• Long polling is a variation of the traditional polling technique where the client sends a request to the server and the server keeps the connection open until new data is available.

• It is often used in web applications to simulate real-time updates without the need for const...read more
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Q3. GraphQL Vs Rest
Ans. 
GraphQL is a query language for APIs that allows clients to request only the data they need, while REST is an architectural style for designing networked applications.
• GraphQL allows clients to request specific data in a single request, reducing over-fetching and under-fetching of data.

• REST uses multiple endpoints for different resources, leading to multiple requests for related data.

• GraphQL provides a strongly typed sc...read more
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Round duration - 90 minutes
Round difficulty - Hard

Test was conducted on Hackerearth. 
Test consist of 3 questions (1 medium strings related question + 1 hard digit dp question + 1 hard lazy segment tree question)

Q1. 
Next Smallest Palindrome Problem Statement
Given a string representation of a number 'S', determine the smallest palindrome that is strictly greater than this number 'N'.
Example:
Input:
3
2
99
3
123
4
4567
...read more
Ans. Palindromic String
In this method, Before we start let us define what is the right half (or right part) and what is left half (or left part) in the string. There can be two cases based on the length of the string:
 
• Case-1: (Odd length string), consider the string “1234567”, the part of the string “123” is the left part(or left half) and the part “567” is the right part(or right half), and the one left(4) is called t...read more
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Q2. 
Count Subarrays with Sum Divisible by K
Given an array ARR and an integer K, your task is to count all subarrays whose sum is divisible by the given integer K.
Input:
The first line of input contains an...read more
Ans. Brute Force (Time Limit Exceed)
The basic idea is that try each and every possible subarray and find the sum of the current subarray and check if the current sum is divisible by ‘K’. 
 
• To implement this approach we use two nested loops and one ‘COUNT’ variable to store all subarray with sum divisible by ‘K’ and initially ‘COUNT’ is ‘0’.
• Iterate outer loop ‘i’ from ‘0’ to ‘N-1’ for every position of ‘ARR’.
• Add che...read more
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Q3. 
Minimum Operations to Equalize Array
Given an integer array ARR of length N where ARR[i] = (2*i + 1), determine the minimum number of operations required to make all the elements of ARR equal. In a single...read more
Ans. Brute Force
• The idea behind this approach is we have to calculate the average of all the elements of the array ‘ARR’ because the sum of all elements of the array always remains constant.
• So calculating the average will help us to virtually divide the elements into two halves around the average i.e left and the right. So calculating the answer for the left half only will be our required answer. It is because in one operat...read more
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Round duration - 90 Minutes
Round difficulty - Medium

Timing : 8:00 am - 9:30 am
The interview took place on google meet. The interviewer gave 1 coding question on google docs and have to write the code on google doc itself.
After 45 minutes a second interviewer came in the same meeting and he also gave a coding question in the same google doc.

Q1. 
Rank from Stream Problem Statement
Given an array of integers ARR and an integer K, determine the rank of the element ARR[K].
Explanation:
The rank of any element in ARR is defined as the number of elem...read more
Ans. Binary Search Tree
The idea is to use the binary search tree.
 
First of all, we will make a binary search tree say ‘BST’ from the given array ‘ARR’ after this we can use ‘BST’ to find the rank of ‘ARR[K]’.
Each node of ‘BST’ will store the data value and size of its left subtree.
 
Here is the complete algorithm:
 
Step 1- Making the ‘BST’ :
 
Let insert(TreeNode* <int> ROOT, int VAL) be a function whi...read more
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Q2. 
Edit Distance Problem Statement
Given two strings S and T with lengths N and M respectively, your task is to find the "Edit Distance" between these strings.
The Edit Distance is defined as the minimum nu...read more
Ans. Recursive Approach
• We will write a recursive approach.
• The base case would be if the length of the first string is 0 then we need to add all the characters of the second string to the first string hence return the length of the second string. Similarly, if the length of the second string is 0 return length of the first string.
• Now the recurrence relation is as follows:
  • If the last characters of two strings are not the same...read more
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Round duration - 60 Minutes
Round difficulty - Medium

Timing : 10:30 am - 11:30 am
The interview took place on google meet. The interviewer gave 1 coding question on google docs and have to write the code on google doc itself.

Q1. 
Smaller Elements Count Problem Statement
Given an array of size N, return a count array such that COUNT[i] equals the number of elements which are smaller than ARR[i] on its right side.
Input:
Input For...read more
Ans. Brute force
The main idea is for every element to count the number of elements less than ARR[i] on its right using a loop.
 
Algorithm:
• Create an ‘ANSWER’ array of size ‘N’ with an initial value 0.
• Run a loop from ‘i’ = 0 to ‘N’. Inside this run another loop from ‘j’ = ‘i+1’ to ‘N’. If  ARR[i] > ARR[j] then increment the ANSWER[i].
• In the end, return the ‘ANSWER’ array.
Space Complexity: O(1)Explanation:
O(1)
&nbs...read more
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Round duration - 15 Minutes
Round difficulty - Easy

Timing : 11:45am - 12:00 pm.
The interview took place on google meet.