UKG Lead Developer Interview Questions and Answers

Round duration - 120 Minutes
Round difficulty - Medium

The test included MCQ questions from SQL, Linux Commands, C/C++ programming, Logical Reasoning, Aptitude
questions. The other section was the coding round, where 2 SQL queries and 2 coding questions were there.

Q1. 
Pythagorean Triplets Detection
Determine if an array contains a Pythagorean triplet by checking whether there are three integers x, y, and z such that x² + y² = z² within the array.
Input:
The first lin...read more
Ans. 
Detect if an array contains a Pythagorean triplet by checking if there are three integers x, y, and z such that x^2 + y^2 = z^2.
• Iterate through all possible triplets of numbers in the array and check if they form a Pythagorean triplet.

• Use a nested loop to generate all possible combinations of three numbers from the array.

• Check if the sum of squares of any three numbers is equal to the square of another number.

• Return 'y...read more
Answered by AI
Add your answer
Q2. 
First Unique Character in a String Problem Statement
Given a string STR consisting of lowercase English letters, identify the first non-repeating character in the string and return it. If no such characte...read more
Ans. 
Identify the first non-repeating character in a string and return it, or '#' if none exists.
• Iterate through the string to count the frequency of each character

• Iterate through the string again to find the first character with frequency 1

• Return the first non-repeating character or '#' if none exists
Answered by AI
Add your answer

Round duration - 70 Minutes
Round difficulty - Medium

This was a standard DSA round where I was asked to solve 2 questions and also code it in a production ready manner . After DS and Algo , I was asked some questions from OOPS and Java followed by some Unix Commands and basic concepts from Operating Systems.

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 duplicates.
Answered by AI
Add your answer
Q2. 
Reverse Linked List Problem Statement
Given a singly linked list of integers, return the head of the reversed linked list.
Example:
Initial linked list: 1 -> 2 -> 3 -> 4 -> NULL
Reversed link...read more
Ans. 
Reverse a singly linked list of integers and return the head of the reversed linked list.
• Iterate through the linked list and reverse the pointers to point to the previous node instead of the next node.

• Use three pointers - prev, current, and next to reverse the linked list in O(N) time and O(1) space complexity.

• Update the head of the reversed linked list as the last node encountered during the reversal process.
Answered by AI
Add your answer
Q3. What are Serialization and Deserialization in Java?
Ans. 
Serialization is the process of converting an object into a byte stream, while deserialization is the reverse process.
• Serialization is used to persist object state or transmit objects over a network.

• Deserialization reconstructs the object from the byte stream.

• Java provides Serializable interface for serialization and ObjectInputStream/ObjectOutputStream classes for deserialization.

• Example: Serializing an object to a fi
Answered by AI
Add your answer
Q4. Can you explain the Singleton Class in Java?
Ans. 
Singleton class in Java ensures that a class has only one instance and provides a global point of access to it.
• Singleton class restricts the instantiation of a class to one object.

• It provides a way to access its unique instance globally.

• Commonly implemented using a private constructor and a static method to return the instance.

• Example: Logger class in a multi-threaded application.
Answered by AI
Add your answer
Q5. Can you explain piping in Unix/Linux?
Ans. 
Piping in Unix/Linux allows the output of one command to be used as the input for another command.
• Piping is done using the | symbol

• It helps in connecting multiple commands together to perform complex operations

• Example: ls -l | grep .txt - This command lists all files in long format and then filters out only the .txt files
Answered by AI
Add your answer

Round duration - 30 Minutes
Round difficulty - Easy

This was a typical HR round with some standard Behavioral questions .

Q1. What is something about you that is not included in your resume?
Add your answer

Round duration - 60 Minutes
Round difficulty - Medium

The interviewer asked me 2 questions related to DS/Algo in this round . Both the questions were of Easy-Medium difficulty and I was also required to code them in a production ready manner.

Q1. 
Maximum Sum Path in a Binary Tree Problem Statement
You are provided with a binary tree consisting of N nodes where each node has an integer value. The task is to determine the maximum sum achievable by a...read more
Ans. 
Find the maximum sum achievable by a simple path between any two nodes in a binary tree.
• Traverse the binary tree to find all possible paths and calculate their sums.

• Keep track of the maximum sum encountered during traversal.

• Consider paths that may include the same node twice.

• Implement a recursive function to explore all possible paths.

• Handle cases where nodes have negative values.
Answered by AI
Add your answer
Q2. 
Intersection of Two Arrays Problem Statement
Given two arrays A and B with sizes N and M respectively, both sorted in non-decreasing order, determine their intersection.
The intersection of two arrays in...read more
Ans. 
The problem involves finding the intersection of two sorted arrays efficiently.
• Use two pointers to iterate through both arrays simultaneously.

• Compare elements at the pointers and move the pointers accordingly.

• Handle cases where elements are equal, and update the intersection array.

• Return the intersection array as the result.
Answered by AI
Add your answer

Round duration - 50 Minutes
Round difficulty - Medium

This round had 2 questions of DS/Algo to solve under 50 minutes and one question related to Operating Systems.

Q1. 
Next Greater Element Problem Statement
You are provided with an array or list ARR containing N positive integers. Your task is to determine the Next Greater Element (NGE) for each element in the array.
T...read more
Ans. 
Find the Next Greater Element for each element in an array.
• Iterate through the array from right to left

• Use a stack to keep track of elements with no greater element to the right

• Pop elements from the stack until finding a greater element or stack is empty
Answered by AI
Add your answer
Q2. 
Number In Arithmetic Progression Problem
Given three integers X, C, and Y, where X is the first term of an arithmetic sequence with a common difference of C, determine if Y is part of this arithmetic sequ...read more
Ans. 
Check if a given number is part of an arithmetic sequence with a given first term and common difference.
• Calculate the arithmetic sequence using the formula: nth term = X + (n-1) * C

• Check if Y is equal to any term in the sequence to determine if it belongs to the sequence

• Return 'True' if Y belongs to the sequence, otherwise return 'False'
Answered by AI
Add your answer
Q3. Can you define process and threads in operating systems?
Ans. 
Processes are instances of programs in execution, while threads are smaller units within a process that can execute independently.
• A process is a program in execution, consisting of code, data, and resources.

• Threads are smaller units within a process that can execute independently.

• Processes have their own memory space, while threads share the same memory space within a process.

• Processes are heavyweight, while threads ar...read more
Answered by AI
Add your answer

Round duration - 50 Minutes
Round difficulty - Medium

This round had 2 questions of DSA of Easy-Medium difficulty and at the end I was asked a Puzzle to check my general problem solving ability.

Q1. 
Max Product Subset Problem Statement
Given an array/list arr of size n, determine the maximum product possible by taking any subset of the array/list arr. Return the result modulo 10^9+7 since the product ...read more
Ans. 
Find the maximum product of a subset of an array modulo 10^9+7.
• Iterate through the array and keep track of the maximum positive product and minimum negative product encountered so far.

• Handle cases where the array contains zeros separately.

• Return the maximum product modulo 10^9+7.
Answered by AI
Add your answer
Q2. 
Populating Next Right Pointers in Each Node
Given a complete binary tree with 'N' nodes, your task is to determine the 'next' node immediately to the right in level order for each node in the given tree.
...read more
Ans. 
Implement a function to update 'next' pointers in a complete binary tree.
• Iterate level by level using a queue

• Connect nodes at each level using 'next' pointers

• Handle null nodes appropriately

• Ensure the tree is a complete binary tree
Answered by AI
Add your answer
Q3. You have two wires of different lengths that are both capable of burning for exactly one hour when ignited at both ends. How can you measure a time interval of 45 minutes using these two wires?
Add your answer

Round duration - 50 Minutes
Round difficulty - Medium

This round consisted of 2 questions from DSA where I was first asked to explain my approach to the interviewer with proper complexity analysis and then code the problems. The interviewer was quite friendly and also provided me some hints when I was stuck.

Q1. 
Stack with getMin Operation
Create a stack data structure that supports not only the usual push and pop operations but also getMin(), which retrieves the minimum element, all in O(1) time complexity witho...read more
Ans. 
Implement a stack with push, pop, top, isEmpty, and getMin operations in O(1) time complexity without using extra space.
• Use two stacks - one to store the actual elements and another to store the minimum element at each level.

• When pushing an element, check if it is smaller than the current minimum and update the minimum stack accordingly.

• When popping an element, also pop from the minimum stack if the popped element is t...read more
Answered by AI
Add your answer
Q2. 
Split Array Into Maximum Subarrays Problem Statement
You are given an integer array arr of size N. Your task is to split the array into the maximum number of subarrays such that the first and last occurre...read more
Ans. 
Given an array, split it into maximum subarrays with first and last occurrence of each element in a single subarray.
• Iterate through the array and keep track of the first and last occurrence of each element.

• Use a hashmap to store the indices of each element.

• Split the array whenever the last occurrence of an element is found.
Answered by AI
Add your answer