NJ Technologies Java Full Stack Developer Interview Questions and Answers

Q1. What are Callbacks ?
Ans. 
Callbacks are functions passed as arguments to other functions, to be executed later.
• Callbacks are commonly used in asynchronous programming to handle events or responses.

• They allow for functions to be executed after another function has finished.

• Callbacks can be used to achieve better modularity and reusability in code.

• Example: setTimeout function in JavaScript takes a callback function as an argument to be executed a
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Q2. Some backend questions
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Q1. DSA - spiral matrix
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Round duration - 50 Minutes
Round difficulty - Medium

Round 2 was a technical interview conducted on Google meet. The interviewer was so much friendly.

Introduce yourself.
Explain your project (as it was mentioned in my resume).
Asked a few questions about my projects, I answered all of them, and he appreciated that.
Questions on os cn dbms and oops followed by 2 data structures problem
Also questions about javascript, typescript, css and html.

Q1. 
Find Indices for Local Minima and Maxima
Given an integer array arr of size N, your task is to determine all indices of local minima and local maxima within the array. Return these indices in a 2-D list, ...read more
Ans. 
The task is to find and return the indices of local minima and local maxima in the given array.
• Iterate through the array and compare each element with its neighbors to determine if it is a local minima or maxima.

• Consider corner elements separately by comparing them with only one neighbor.

• Store the indices of local minima and maxima in separate lists.

• If there are no local minima or maxima, return -1 as the only row elem
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Q2. 
Rotational Equivalence of Strings Problem Statement
Given two strings 'P' and 'Q' of equal length, determine if string 'P' can be transformed into string 'Q' by cyclically rotating it to the right any num...read more
Ans. 
The task is to check if one string can be converted into another string by cyclically rotating it to the right any number of times.
• Check if the lengths of the two strings are equal. If not, return 0.

• Concatenate the first string with itself and check if the second string is a substring of the concatenated string.

• If the second string is a substring, return 1. Otherwise, return 0.
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Round duration - 50 Minutes
Round difficulty - Medium

I was asked to explain my project and the difficulties I faced while implementing it followed by 2 coding questions.
Interviewer was very senior this time but helped me a lot during the process. Asked some sql queries like to find count of the books by their category had to use group by.

Q1. 
Minimum Jumps Problem Statement
Bob and his wife are in the famous 'Arcade' mall in the city of Berland. This mall has a unique way of moving between shops using trampolines. Each shop is laid out in a st...read more
Ans. 
This question asks for the minimum number of trampoline jumps a person needs to make in order to reach the last shop in a mall.
• The shops in the mall are laid out in a straight line and each shop has a constant value representing the maximum distance it can be jumped to.

• The person starts at shop 0 and wants to reach the last shop, shop N-1.

• If it is impossible to reach the last shop, the function should return -1.

• The fun...read more
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Round duration - 20 Minutes
Round difficulty - Easy

Asked me Tell me something about myself. She also described the way ZopSmart does business.