Zolo Software Developer Interview Questions and Answers

Round duration - 60 minutes
Round difficulty - Easy

It comprised of general aptitude questions and two coding questions. It was an offline test.

Q1. 
N Queens Problem
Given an integer N, find all possible placements of N queens on an N x N chessboard such that no two queens threaten each other.
Explanation:
A queen can attack another queen if they ar...read more
Ans. 
The N Queens Problem involves finding all possible placements of N queens on an N x N chessboard where no two queens threaten each other.
• Use backtracking algorithm to explore all possible configurations.

• Keep track of rows, columns, and diagonals to ensure queens do not attack each other.

• Generate and print valid configurations where queens are placed safely.

• Consider constraints and time limit for efficient solution.

• Exam...read more
Answered by AI
Add your answer
Q2. 
Sort 0 1 2 Problem Statement
Given an integer array arr of size 'N' containing only 0s, 1s, and 2s, write an algorithm to sort the array.
Input:
The first line contains an integer 'T' representing the n...read more
Ans. 
Sort an integer array containing only 0s, 1s, and 2s in linear time complexity.
• Use three pointers to keep track of the positions of 0s, 1s, and 2s in the array.

• Iterate through the array and swap elements based on the values encountered.

• Achieve sorting in a single scan over the array without using any extra space.
Answered by AI
Add your answer

Round duration - 60 minutes
Round difficulty - Easy

After having a technical discussion about my CV. He gave me two questions to code.

Q1. 
Ninja and Substrings Problem Statement
Ninja has to determine all the distinct substrings of size two that can be formed from a given string 'STR' comprising only lowercase alphabetic characters. These su...read more
Ans. 
Find all unique contiguous substrings of size two from a given string.
• Iterate through the string and extract substrings of size two

• Use a set to store unique substrings

• Return the set as an array of strings
Answered by AI
Add your answer
Q2. 
Cycle Detection in a Singly Linked List
Determine if a given singly linked list of integers forms a cycle or not.
A cycle in a linked list occurs when a node's next points back to a previous node in the ...read more
Ans. 
Detect if a singly linked list forms a cycle by checking if a node's next points back to a previous node.
• Traverse the linked list using two pointers, one moving one step at a time and the other moving two steps at a time.

• If the two pointers meet at any point, there is a cycle in the linked list.

• If one of the pointers reaches the end of the list (null), there is no cycle.
Answered by AI
Add your answer

Round duration - 30 minutes
Round difficulty - Easy

This was supposed to be the HR round but out of surprise the interviewer started by giving me a question to code. 
After I approached this question with the right solution he just asked about my family. After that he said to wait. After half an hour the results were announced. A total of three students were hired and I was amongst one of them.

Q1. 
Balanced Parentheses Combinations
Given an integer N representing the number of pairs of parentheses, find all the possible combinations of balanced parentheses using the given number of pairs.
Explanati...read more
Ans. 
Generate all possible combinations of balanced parentheses for a given number of pairs.
• Use recursion to generate all possible combinations of balanced parentheses.

• Keep track of the number of open and close parentheses used in each combination.

• Return the valid combinations as an array of strings.
Answered by AI
Add your answer

Q1. Launch modes on android
Ans. 
Launch modes on Android determine how a new instance of an activity is associated with the current task.
• Standard: Creates a new instance of the activity in the task's stack

• SingleTop: If an instance of the activity already exists at the top of the stack, it will not be recreated

• SingleTask: Activity is always at the root of the task and no other activities can be on top of it

• SingleInstance: Similar to SingleTask, but the
Answered by AI
Add your answer

Questios based on Activity backstacks

Data structure - rainwater trapping

Q1. OOPs concept, core java, sql
Add your answer
Q2. Car parking lot problem - system design
Ans. 
Design a car parking lot system
• Determine the size and capacity of the parking lot

• Create a database to store information about available spots and occupied spots

• Develop a system to track the entry and exit of vehicles

• Implement a payment system for parking fees

• Incorporate security measures such as CCTV cameras and security personnel

• Provide a user-friendly interface for customers to locate available spots and make payment
Answered by AI
Add your answer

Q1. Rapid fire questions
Add your answer
Q2. More java springboot
Add your answer

Round duration - 120 Minutes
Round difficulty - Medium

Machine Coding Round
2 Hours in Total
15 Mins for Question Explaination and Doubts
1.5 Hours for coding
15 mins to discuss the approach 

Timing - 3 to 5 pm (They are flexible)
Interviewer was very patient and helped me understand the question

Round duration - 60 Minutes
Round difficulty - Medium

2 Data Strucutre Questions
Timing 5-6 pm (They are flexible)
Google Meet
Online IDE

Q1. 
Unique Binary Search Trees Problem Statement
Given an integer 'N', your task is to compute the number of structurally unique BSTs (binary search trees) that can be formed using an exact number of 'N' uniq...read more
Ans. 
The task is to compute the number of structurally unique BSTs that can be formed using an exact number of unique values.
• Use dynamic programming to solve the problem efficiently.

• The number of structurally unique BSTs can be calculated using Catalan numbers.

• For N nodes, the number of structurally unique BSTs is given by the Nth Catalan number.

• Example: For N=3, the number of structurally unique BSTs is 5.
Answered by AI
Add your answer
Q2. 
Subsequences of String Problem Statement
You are provided with a string 'STR' that consists of lowercase English letters ranging from 'a' to 'z'. Your task is to determine all non-empty possible subsequen...read more
Ans. 
Generate all possible subsequences of a given string.
• Use recursion to generate all possible subsequences by including or excluding each character in the string.

• Maintain a current index to keep track of the characters being considered.

• Append the current character to each subsequence generated so far.

• Recursively call the function with the next index to include or exclude the next character.

• Base case: When the current ind...read more
Answered by AI
Add your answer

Round duration - 60 Minutes
Round difficulty - Easy

HIRING MANAGER ROUND

Discussion about the organisation now questions

Q1. Introduce yourself
Ans. 
I am a software developer with 5 years of experience in Java and Python. I have a passion for problem-solving and creating innovative solutions.
• 5 years of experience in Java and Python

• Passionate about problem-solving

• Innovative solutions driven
Answered by AI
Add your answer
Q2. Were u see after 5 years
Ans. 
In 5 years, I see myself as a senior software developer leading a team and working on cutting-edge technologies.
• Leading a team of developers on innovative projects

• Working with cutting-edge technologies like AI and blockchain

• Continuing to learn and grow in my career

• Possibly pursuing further education or certifications

• Contributing to open source projects
Answered by AI
Add your answer

Basic JavaScript Interview

Q1. What is closure
Ans. 
Closure is a function that has access to its own scope, as well as the outer scope in which it was defined.
• Closure allows a function to access variables from its outer scope even after the outer function has finished executing.

• It is created whenever a function is defined within another function.

• Closure is commonly used in JavaScript for maintaining state in asynchronous operations.
Answered by AI
Add your answer
Q2. What are promise
Ans. 
Promises are objects representing the eventual completion or failure of an asynchronous operation.
• Promises are used to handle asynchronous operations in JavaScript.

• They can be in one of three states: pending, fulfilled, or rejected.

• Promises can be chained together using .then() method.

• They help avoid callback hell and make code more readable.

• Example: Fetching data from an API returns a promise that resolves with the da
Answered by AI
Add your answer