400+ Amdocs Interview Questions and Answers

Given a string of lowercase English letters, find the first non-repeating character at each point in the stream.

• Create a hashmap to store the frequency of each character as it appears in the stream.

• Iterate through the stream and check the frequency of each character to find the first non-repeating character.

• Output the first non-repeating character at each point in the stream.

Find the third largest element in an array of distinct integers.

• Sort the array in descending order and return the element at index 2.

• Handle cases where there are less than 3 elements in the array separately.

• Make sure to handle duplicates properly.

Return all distinct palindromic substrings of a given string in alphabetical order.

• Iterate through all possible substrings of the given string.

• Check if each substring is a palindrome.

• Store distinct palindromic substrings in alphabetical order.

Detect if a singly linked list forms a cycle by checking if a node's next pointer points back to a previous node.

• Use Floyd's Cycle Detection Algorithm to determine if there is a cycle in the linked list.

• Maintain two pointers, one moving at twice the speed of the other, and check if they meet at any point.

• If the fast pointer reaches the end of the list (null), there is no cycle.

• If the fast and slow pointers meet at some point, there is a cycle in the linked list.

Implement Merge Sort algorithm to sort a sequence of numbers in non-descending order.

• Divide the input array into two halves recursively until each array has only one element.

• Merge the sorted halves to produce a completely sorted array.

• Time complexity of Merge Sort is O(n log n).

• Example: Input: [3, 1, 4, 1, 5], Output: [1, 1, 3, 4, 5]

Check if a Pythagorean triplet exists in a given array of integers.

• Iterate through all possible combinations of three numbers in the array and check if they form a Pythagorean triplet.

• Use a nested loop to generate all possible combinations efficiently.

• Check if the sum of squares of two numbers is equal to the square of the third number.

Check if two strings are anagrams of each other by comparing their sorted characters.

• Sort the characters of both strings and compare them.

• Use a dictionary to count the frequency of characters in each string and compare the dictionaries.

• Ensure both strings have the same length before proceeding with the comparison.

• Example: For input 'spar' and 'rasp', after sorting both strings, they become 'aprs' which are equal, so return True.

Calculate the Nth Fibonacci number efficiently using dynamic programming.

• Use dynamic programming to store and reuse previously calculated Fibonacci numbers.

• Start with base cases F(1) and F(2) as 1, then calculate subsequent Fibonacci numbers.

• Optimize the solution to avoid redundant calculations and improve efficiency.

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.

Find the index of the first unique character in a given string, return -1 if no unique characters are found.

• Create a hashmap to store the frequency of each character in the string.

• Iterate through the string and find the first character with frequency 1.

• Return the index of the first unique character or -1 if no unique characters are found.

To measure 4L of water using 3L and 5L jars, fill the 5L jar, pour 3L into the 3L jar, empty the 3L jar, and pour the remaining 2L from the 5L jar into the 3L jar. Finally, fill the 5L jar again and pour 1L into the 3L jar. Now, the 5L jar contains 4L of water.

• Fill the 5L jar completely

• Pour 3L from the 5L jar into the 3L jar

• Empty the 3L jar

• Pour the remaining 2L from the 5L jar into the 3L jar

• Fill the 5L jar again

• Pour 1L from the 5L jar into the 3L jar

Find the total weight of the Minimum Spanning Tree in a graph using Kruskal's algorithm.

• Implement Kruskal's algorithm to find the Minimum Spanning Tree.

• Sort the edges based on their weights and add them to the MST if they don't form a cycle.

• Keep track of the total weight of the MST and return it as the output.

Find the maximum number of points that can be aligned in a straight line on a 2-D plane.

• Iterate through each pair of points and calculate the slope between them.

• Store the slope in a hashmap and keep track of the frequency of each slope.

• The maximum frequency of slopes + 1 gives the maximum number of points on a straight line.

Find the maximum sum of an increasing subsequence of length K in an array.

• Iterate through the array and maintain a dynamic programming table to store the maximum sum of increasing subsequences of different lengths.

• For each element, check all previous elements to find the increasing subsequences and update the maximum sum accordingly.

• Return the maximum sum of the increasing subsequence of length K.

• Example: For input [1, 2, 5, 4, 8] and K = 3, the maximum sum increasing subsequ...read more

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.

To check for integer overflow when multiplying two integers, use the properties of integer overflow and check if the result is within the valid range of the integer type.

• Check if the signs of the two integers are the same to avoid overflow in case of multiplication.

• Use the properties of integer overflow to detect if the result exceeds the maximum or minimum value of the integer type.

• Consider using a larger data type or a library that supports arbitrary-precision arithmetic if...read more

Reverse a given stack of integers using recursion without using extra space or loops.

• Use recursion to pop all elements from the original stack and store them in function call stack

• Once the stack is empty, push the elements back in reverse order using recursion

• Use the top(), pop(), and push() methods to manipulate the stack

Use SQL query with GROUP BY and HAVING clause to delete duplicate emails from a database.

• Use GROUP BY clause to group emails together

• Use HAVING clause to filter out groups with more than one email

• Use DELETE statement to remove duplicate emails

Identify the first non-repeating character in a given 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

Implement a function to convert a string to an integer, ignoring non-numeric characters and considering negative numbers.

• Iterate through the characters of the string and check if they are numeric.

• Handle negative numbers by checking the first character of the string.

• Ignore non-numeric characters while converting the string to an integer.

• Return 0 if there are no numbers in the string.

• Ensure the resulting number is within the given constraints.

Constructor is a special method used to initialize objects, while a method is a regular function that performs a specific task.

• Constructor is called automatically when an object is created, while a method needs to be called explicitly.

• Constructors have the same name as the class, while methods have unique names.

• Constructors do not have a return type, while methods have a return type.

• Example: Constructor - public ClassName() { // initialization code }, Method - public void met...read more

Use three threads to print numbers from 1 to 100 in sequence.

• Create three threads, each responsible for printing numbers in a specific range (e.g. 1-33, 34-66, 67-100).

• Use synchronization mechanisms like mutex or semaphore to ensure proper sequencing of numbers.

• Thread 1 prints numbers 1-33, Thread 2 prints numbers 34-66, Thread 3 prints numbers 67-100.

DELETE removes specific rows from a table, while TRUNCATE removes all rows and resets auto-increment values.

• DELETE is a DML command, while TRUNCATE is a DDL command.

• DELETE can be rolled back, while TRUNCATE cannot be rolled back.

• DELETE triggers ON DELETE triggers, while TRUNCATE does not trigger any triggers.

• DELETE is slower as it maintains logs, while TRUNCATE is faster as it does not maintain logs.

• Example: DELETE FROM table_name WHERE condition; TRUNCATE table_name;

Count the number of subarrays where the number of 0s is equal to the number of 1s in a given array of 0s and 1s.

• Iterate through the array and keep track of the count of 0s and 1s encountered so far.

• Use a hashmap to store the count of 0s and 1s encountered at each index.

• For each index, check if the count of 0s and 1s encountered so far are equal. If yes, increment the total count of subarrays.

Use a 3-liter can and a 5-liter can to measure exactly 4 liters of water.

• Fill the 3-liter can and pour it into the 5-liter can, leaving 2 liters in the 3-liter can.

• Empty the 5-liter can, then pour the remaining 2 liters from the 3-liter can into the 5-liter can.

• Fill the 3-liter can again and pour it into the 5-liter can, which already has 2 liters, making it 4 liters.

The problem involves determining the minimum number of umbrellas required to shelter a specific number of people based on the capacity of each umbrella.

• Iterate through the array of umbrella capacities to find the combination that covers exactly 'M' people.

• Keep track of the minimum number of umbrellas used to cover 'M' people.

• If it is not possible to cover 'M' people exactly, return -1.

• Example: For input [2, 3, 4] and M=5, the minimum number of umbrellas required is 2 (2-capac...read more

Overloading is having multiple methods in the same class with the same name but different parameters, while overriding is implementing a method in a subclass that is already defined in the superclass.

• Overloading involves multiple methods with the same name but different parameters.

• Overriding involves implementing a method in a subclass that is already defined in the superclass.

• Overloading is determined at compile time based on the method signature, while overriding is determi...read more

SOLID principles are a set of five design principles that help make software designs more understandable, flexible, and maintainable.

• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open/Closed Principle: Objects should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Subtypes should be substitutable for their base types.

• I - Interface Segregation Principle: Clients should not be forced to depend on inte...read more

To take a backup of a table in MySQL, you can use the mysqldump command.

• Use the mysqldump command followed by the database name and table name to backup a specific table.

• You can also specify the username and password for the MySQL server using the -u and -p flags.

• To backup all tables in a database, use the --all-databases flag with the mysqldump command.

Singleton class is a class that can only have one instance at a time.

• It is used to control access to a shared resource or limit the instantiation of a class to one object.

• To make a class singleton, make the constructor private and provide a static method to get the instance.

• Example: public class Singleton { private static Singleton instance = new Singleton(); private Singleton() {} public static Singleton getInstance() { return instance; } }

Detect if an array contains a Pythagorean triplet by checking if x^2 + y^2 = z^2.

• Iterate through all possible combinations of three numbers in the array.

• Check if the sum of squares of any two numbers is equal to the square of the third number.

• Return 'yes' if a Pythagorean triplet is found, otherwise return 'no'.

Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity, while denormalization is the process of intentionally adding redundancy to improve query performance.

• Normalization involves breaking down a table into smaller tables and defining relationships between them to reduce redundancy and dependency.

• Denormalization involves combining tables or adding redundant data to improve query performance by reducing the number of joins...read more

Challenges faced in RPA experience and how resolved

• One challenge was automating a process with multiple decision points, resolved by creating a decision tree

• Another challenge was handling exceptions, resolved by implementing exception handling mechanisms

• Integration with legacy systems was a challenge, resolved by creating custom connectors

• Lack of standardization in input data was a challenge, resolved by implementing data validation and cleansing mechanisms

Find all paths in a binary tree where the sum of node values equals a given value 'K'.

• Traverse the binary tree using depth-first search (DFS) and keep track of the current path and its sum.

• When reaching a leaf node, check if the sum equals 'K' and add the path to the result.

• Continue DFS traversal for both left and right children, passing updated path and sum.

• Return the list of paths that sum up to 'K'.

The task is to determine if a given integer is a Fibonacci number or not.

• Iterate through the Fibonacci sequence until the current number exceeds the given integer 'N'.

• Check if the given integer 'N' matches any number in the Fibonacci sequence.

• If a match is found, output 'YES'; otherwise, output 'NO'.

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 file or sending it over a network.

Remove the Kth node from the end of a singly linked list.

• Traverse the linked list to find the length 'N'.

• Calculate the position to delete from the beginning as 'N - K + 1'.

• Delete the node at the calculated position.

• Handle edge cases like deleting the head or tail node.

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, static method, and a static instance variable.

• Example: Logger class in Java can be implemented as a Singleton to ensure only one instance is used for logging.

Implement a priority queue using Heap data structure with functions like push, pop, getMaxElement, and isEmpty.

• Implement push() function to insert element into the priority queue.

• Implement pop() function to delete the largest element from the queue.

• Implement getMaxElement() function to return the largest element.

• Implement isEmpty() function to check if the queue is empty.

vptr stands for virtual pointer and vptr table is a table of function pointers used in polymorphism in C++.

• vptr is a hidden member variable in C++ objects that points to the vptr table.

• vptr table is a table of function pointers that maps virtual functions to their addresses.

• Each object of a class with virtual functions has its own vptr and shares the same vptr table with other objects of the same class.

• vptr and vptr table are created when an object of a class with virtual fun...read more

Check if a given string is a palindrome after removing special characters, spaces, and converting to lowercase.

• Remove special characters and spaces from the input string

• Convert the string to lowercase

• Check if the modified string is a palindrome by comparing characters from start and end

Serialization is the process of converting an object into a stream of bytes, while deserialization is the reverse process.

• Serialization is used for data storage, transmission, and object persistence.

• Deserialization is used to recreate the original object from the serialized data.

• Examples of serialization formats include JSON, XML, and binary formats like Protocol Buffers and Apache Avro.

• Serialization can also be used for deep copying objects.

• Deserialization can be vulnerable ...read more

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 chaining multiple commands together

• Example: ls -l | grep .txt

Find the node where two linked lists merge

• Traverse both lists to find their lengths and the difference in lengths

• Move the pointer of the longer list by the difference in lengths

• Traverse both lists simultaneously until they meet at the merging node

Calculate the Nth Fibonacci number using the given formula and constraints.

• Implement a function to calculate the Nth Fibonacci number using the formula F(n) = F(n-1) + F(n-2) with base cases F(1) = F(2) = 1.

• Use dynamic programming or recursion to efficiently compute the Fibonacci number for large N values.

• Ensure the input N is within the constraints 1 <= N <= 10000.

• Example: For N = 5, the output should be 5 as the 5th Fibonacci number is 5.

Print all prime numbers within the range from 2 to N.

• Iterate from 2 to N and check if each number is prime

• A prime number is a number greater than 1 that has no positive divisors other than 1 and itself

• Use a nested loop to check divisibility by numbers less than the current number

Program to find duplicate elements in arraylist with minimum iterations

• Use HashSet to store unique elements and ArrayList to store duplicates

• Iterate through the ArrayList only once

• Use contains() method to check if element is already in HashSet

The task is to determine the total number of ways to make change for a specified value using given denominations.

• Create a function that takes in the number of denominations, the denominations array, and the value to make change for as input parameters.

• Use dynamic programming to iterate through all possible combinations of coins to make the change.

• Keep track of the number of ways to make change for each value from 0 to the target value.

• Return the total number of ways to make c...read more

Weigh 3 groups of 3 balls each, then weigh 2 heaviest balls from the heaviest group to find the heaviest ball.

• Divide the 9 balls into 3 groups of 3 balls each.

• Weigh the first 2 groups against each other.

• If one group is heavier, weigh 2 balls from that group against each other to find the heaviest ball.

• If both groups weigh the same, weigh the third group to find the heaviest group.

• Weigh 2 heaviest balls from the heaviest group to find the heaviest ball.

Check for a loop in a linked list by using two pointers moving at different speeds.

• Use two pointers, one moving at double the speed of the other.

• If there is a loop, the two pointers will eventually meet at the same node.

• Example: 1 -> 2 -> 3 -> 4 -> 5 -> 2 (loop back to 2), the two pointers will meet at node 2.

Sort an array of 0s, 1s, and 2s in non-decreasing order.

• Use a counting sort algorithm to count the occurrences of 0s, 1s, and 2s in the array.

• Then reconstruct the array by placing the counted elements in order.

• Time complexity of the counting sort algorithm is O(N).

Merge two sorted linked lists into a single sorted linked list with linear time complexity and constant space usage.

• Create a dummy node to start the merged list

• Compare the values of the two linked lists and add the smaller value to the merged list

• Move the pointer of the merged list and the pointer of the smaller value list forward

• Continue this process until one of the lists is fully traversed

• Append the remaining elements of the other list to the merged list

• Return the head of ...read more

Swap two numbers 'a' and 'b' and output the swapped values.

• Create a temporary variable to store one of the numbers before swapping

• Assign the value of 'a' to 'b' and the temporary variable to 'a'

• Output the swapped values as 'b' followed by 'a'

Answering coding questions on string reversal, variable swapping, and pattern printing.

• For string reversal, use a loop to iterate through the string and append each character to a new string in reverse order.

• To separate vowels and consonants, use a loop to iterate through the string and check if each character is a vowel or consonant.

• To swap two variables without a third variable, use arithmetic operations or XOR bitwise operator.

• For pattern printing, use nested loops to prin...read more

Const reference in copy constructor is used to avoid unnecessary object copying and improve performance.

• Const reference allows us to pass objects by reference without modifying them.

• Using const reference in copy constructor avoids creating a temporary copy of the object being passed.

• It helps in preventing unnecessary memory allocation and improves performance.

• Const reference ensures that the original object is not modified during the copy construction process.

Write a SQL query to join two tables on a common attribute and select matching records.

• Use the JOIN keyword to combine tables A and B on the common attribute ID

• Specify the common attribute in the ON clause of the JOIN

• Select the desired columns (ID_NAME) from the joined tables

Program to display a pattern of numbers in a pyramid shape.

• Use nested loops to print the numbers in the desired pattern.

• The outer loop controls the number of rows and the inner loop prints the numbers in each row.

• Use a variable to keep track of the number to be printed in each row.

• Print a new line after each row is printed.

Design a Least Recently Used (LRU) cache data structure that supports get and put operations with capacity constraint.

• Implement a doubly linked list to keep track of the order of keys based on their recent usage.

• Use a hashmap to store key-value pairs for quick access and update.

• When capacity is reached, evict the least recently used item before inserting a new item.

Swapping of numbers can be done using call by value, address and reference.

• Call by value: Pass the values of variables as arguments to the function. Swap the values inside the function.

• Call by address: Pass the addresses of variables as arguments to the function. Swap the values using pointers inside the function.

• Call by reference: Pass the references of variables as arguments to the function. Swap the values using references inside the function.

To create a backup table in MySQL, use the CREATE TABLE statement with SELECT INTO.

• Use the CREATE TABLE statement with SELECT INTO to create a backup table.

• Specify the name of the backup table and the name of the original table.

• Use the SELECT INTO statement to copy the data from the original table to the backup table.

• Example: CREATE TABLE backup_table SELECT * FROM original_table;

• Make sure to regularly update the backup table to ensure data consistency.

OOPs concepts include Encapsulation, Inheritance, Abstraction, and Polymorphism.

• Encapsulation: bundling of data and methods that operate on that data

• Inheritance: creating new classes from existing ones

• Abstraction: hiding implementation details and showing only necessary information

• Polymorphism: ability of objects to take on multiple forms or behaviors

CSS position properties are used to position elements on a web page.

• The position property specifies the type of positioning method used for an element.

• The top, bottom, left, and right properties are used to position the element.

• The static, relative, absolute, fixed, and sticky values are used for the position property.

• Static is the default value and elements are positioned according to the normal flow of the page.

• Relative positions the element relative to its normal position....read more

Race horses in groups of 5, then race the winners to determine the top 3 fastest horses.

• Divide the 25 horses into 5 groups of 5 horses each.

• Race the horses in each group to determine the fastest horse in each group.

• Race the winners from each group to determine the top 3 fastest horses.

Key concepts of OOP include encapsulation, inheritance, polymorphism, and abstraction.

• Encapsulation: Bundling data and methods that operate on the data into a single unit (object).

• Inheritance: Allowing a class to inherit properties and behavior from another class.

• Polymorphism: Objects of different classes can be treated as objects of a common superclass.

• Abstraction: Hiding complex implementation details and showing only the necessary features to the outside world.

HashMap is a data structure that stores key-value pairs and uses hashing to quickly retrieve values based on keys.

• HashMap internally uses an array of linked lists to store key-value pairs.

• When a key-value pair is added, the key is hashed to determine the index in the array where the pair will be stored.

• If multiple keys hash to the same index (collision), a linked list is used to store these pairs.

• To retrieve a value, the key is hashed again to find the index and then the link...read more

A multi-threading program to print 1 2 1 2 using 2 threads.

• Create two threads and pass a flag to each thread to print either 1 or 2.

• Use a synchronization mechanism like mutex or semaphore to ensure alternate printing.

• Join the threads to wait for their completion.

Inner Join in SQL is used to combine rows from two or more tables based on a related column between them.

• Inner Join returns only the rows that have matching values in both tables

• It is the most common type of join used in SQL

• Syntax: SELECT columns FROM table1 INNER JOIN table2 ON table1.column = table2.column

• Example: SELECT orders.order_id, customers.customer_name FROM orders INNER JOIN customers ON orders.customer_id = customers.customer_id

Right outer join is a type of join operation that returns all the rows from the right table and the matching rows from the left table.

• Right outer join is denoted by the RIGHT JOIN keyword in SQL.

• It is used to combine rows from two tables based on a related column.

• In the result set, unmatched rows from the right table will have NULL values for the columns of the left table.

• A real-world scenario for using a right outer join is when analyzing customer data and sales data. The ri...read more

Convert string to integer without using inbuilt function

• Iterate through each character and multiply by 10 and add the integer value of the character

• Use ASCII values to convert character to integer

• Handle negative numbers separately

Multithreading is the ability of a CPU to execute multiple threads concurrently. POSIX thread is a standard for thread creation and management.

• Multithreading allows multiple threads to run concurrently, improving performance and responsiveness.

• POSIX thread (pthread) is a standard for creating and managing threads in Unix-based systems.

• Thread synchronization is the coordination of threads to ensure that they do not interfere with each other's execution.

• Mutexes, semaphores, and...read more

Garbage collector in Java is an automatic memory management system that frees up memory by removing unused objects.

• Garbage collector runs in the background and identifies objects that are no longer in use

• It frees up memory by removing those unused objects

• It helps prevent memory leaks and improves performance

• Java provides different types of garbage collectors such as Serial, Parallel, CMS, and G1

• Example: If an object is created but not used anymore, the garbage collector will ...read more

Views in SQL are virtual tables that are generated based on the result set of a SELECT query.

• Views are used to simplify complex queries by storing them as virtual tables.

• They can be used to restrict access to certain columns or rows of a table.

• Views do not store data themselves, but display data from the underlying tables.

• Changes made to the underlying tables are reflected in the views.

• Example: CREATE VIEW vw_employee AS SELECT emp_id, emp_name FROM employees;

Java is platform-independent because the code is compiled into bytecode which can run on any platform with a JVM, making the JVM platform-dependent.

• Java code is compiled into bytecode, which is a platform-independent intermediate code

• The JVM interprets and executes the bytecode on different platforms

• The JVM acts as a layer of abstraction between the Java code and the underlying platform

• The JVM is platform-dependent because it needs to be implemented specifically for each plat...read more

To determine which switch controls which bulb with only one entry to the bulb room.

• Turn on the first switch and leave it on for a few minutes, then turn it off.

• Turn on the second switch and enter the room.

• The bulb that is on corresponds to the second switch, the bulb that is off and warm corresponds to the first switch, and the bulb that is off and cold corresponds to the third switch.

Volatile keyword is used to indicate that a variable's value can be changed unexpectedly.

• It is used in multi-threaded programming to ensure that the value of a variable is always up-to-date and consistent across all threads.

• It prevents the compiler from optimizing code that accesses the variable, ensuring that the variable is always read from memory and not from a cache.

• Examples include hardware registers, shared memory, and global variables that can be accessed by multiple t...read more

Essential UNIX commands include ls, cd, pwd, mkdir, and rm.

• ls - list directory contents

• cd - change directory

• pwd - print working directory

• mkdir - make directory

• rm - remove files or directories

Program to reverse a string in any language

• Create an empty string variable to store the reversed string

• Loop through the original string from the end to the beginning

• Append each character to the empty string variable

• Return the reversed string

SDLC, STLC, Waterfall model, smoke testing, black box testing, quality, stub and driver, levels of testing, UAT, system testing, defect, defect life cycle.

• SDLC (Software Development Life Cycle) is a process followed for software development.

• STLC (Software Testing Life Cycle) is a process followed for software testing.

• Waterfall model is a linear sequential approach to software development.

• Smoke testing is a preliminary test to check if the software is stable enough for further...read more

Primary key uniquely identifies a record in a table, while unique key ensures no duplicate values in a column.

• Primary key is used to uniquely identify each record in a table

• Primary key does not allow NULL values

• Unique key ensures that all values in a column are unique

• Unique key allows NULL values, except for the column with unique constraint

• A table can have only one primary key, but multiple unique keys

Left Outer Join includes all records from the left table and matching records from the right table. Right Outer Join includes all records from the right table and matching records from the left table.

• Left Outer Join returns all records from the left table and the matched records from the right table. Unmatched records from the right table will have NULL values.

• Right Outer Join returns all records from the right table and the matched records from the left table. Unmatched reco...read more

To find the second highest salary in a table, you can use a SQL query with the ORDER BY and LIMIT clauses.

• Use a SQL query to select the distinct salaries in descending order: SELECT DISTINCT salary FROM table_name ORDER BY salary DESC

• Use the LIMIT clause to retrieve the second row: LIMIT 1,1

• Combine both queries to find the second highest salary: SELECT DISTINCT salary FROM table_name ORDER BY salary DESC LIMIT 1,1

Different types of joins in SQL include inner join, left join, right join, and full outer join.

• Inner join: Returns rows when there is a match in both tables.

• Left join: Returns all rows from the left table and the matched rows from the right table.

• Right join: Returns all rows from the right table and the matched rows from the left table.

• Full outer join: Returns rows when there is a match in either table.

Interfaces in software development define a contract for classes to implement certain methods or properties.

• Interfaces in programming are like blueprints that define the structure of a class.

• Classes that implement an interface must provide definitions for all the methods and properties specified in the interface.

• Interfaces allow for polymorphism and code reusability.

• Example: An interface 'Shape' may have methods like 'calculateArea' and 'calculatePerimeter', which classes lik...read more

The maximum number of pieces a circular cake can be divided into with a specified number of straight cuts.

• Each cut will increase the number of pieces by 1

• The formula to calculate the maximum number of pieces is n(n+1)/2 + 1, where n is the number of cuts

• For example, with 3 cuts, the maximum number of pieces is 7: 3(3+1)/2 + 1 = 7

The life cycle of a thread in Java involves creation, running, waiting, and termination.

• A thread is created using the 'new' keyword or by implementing the Runnable interface.

• The thread starts running when the start() method is called.

• During execution, a thread can enter a waiting state using methods like sleep() or wait().

• A thread terminates when its run() method completes or when the stop() method is called.

Run time polymorphism in C++ allows objects of different classes to be treated as objects of a common parent class.

• Run time polymorphism is achieved through virtual functions and function overriding.

• It allows a function to behave differently based on the object it is called on.

• Example: Using a base class pointer to call a virtual function that is overridden in a derived class.

Interview questions for Automation Test Engineer

• To run failed test case, use failed.xml

• Click can be used via Actions class or JavascriptExecutor

• Array programs: reverse, second highest number

• Constructor in abstract class

• Test plan and scenario definition

• Roles and responsibilities in current organization

• Disable test cases using keyword or include/exclude in suite

• Polymorphism concept

• Unix commands used in day to day activity

• TestNG annotations and keywords

• Code for scroll up and dow...read more

Views in SQL are virtual tables that display data from one or more tables.

• Views are created using SELECT statements.

• They can be used to simplify complex queries.

• They can also be used to restrict access to sensitive data.

• Views do not store data themselves, but rather display data from other tables.

• Example: CREATE VIEW myView AS SELECT * FROM myTable WHERE column = 'value';

Null pointer points to nothing, while dangling pointer points to memory that has been deallocated.

• Null pointer is a pointer that does not point to any memory location.

• Dangling pointer is a pointer that points to memory that has been deallocated.

• Accessing a null pointer will result in a segmentation fault.

• Accessing a dangling pointer can lead to unpredictable behavior or crashes.

• Example: int* nullPtr = nullptr; int* danglingPtr = new int; delete danglingPtr; danglingPtr = null...read more

My expected CTC would depend on the job role, company size, location, and benefits package.

• Consider the job role and responsibilities when determining expected CTC.

• Research industry standards and average salaries for similar positions.

• Factor in the company size and location, as cost of living varies.

• Take into account additional benefits such as healthcare, retirement plans, and bonuses.

• Be prepared to negotiate based on your skills, experience, and market demand.

Constructor is used to initialize an object while method is used to perform an action on an object.

• Constructor is called automatically when an object is created while method is called explicitly.

• Constructor has the same name as the class while method has a unique name.

• Constructor does not have a return type while method has a return type.

• Example of constructor: public class Car { public Car() { //initialize variables } }

• Example of method: public void startEngine() { //perform...read more

DELETE removes specific rows from a table, while TRUNCATE removes all rows and resets auto-increment values.

• DELETE is a DML command, while TRUNCATE is a DDL command.

• DELETE can be rolled back, while TRUNCATE cannot be rolled back.

• DELETE triggers delete triggers, while TRUNCATE does not trigger them.

• DELETE is slower as it logs individual row deletions, while TRUNCATE is faster as it logs the deallocation of the data pages.

• Example: DELETE FROM table_name WHERE condition; TRUNCAT...read more

Program to reverse a string in minimum iteration

• Use two pointers, one at the start and one at the end of the string

• Swap the characters at the two pointers and move the pointers towards each other

• Repeat until the pointers meet in the middle of the string

The best technique to generate automated test report is to use a reporting tool that integrates with the automation framework.

• Choose a reporting tool that supports the programming language and automation framework being used

• Configure the reporting tool to generate reports in the desired format

• Include relevant information in the report such as test case name, status, and duration

• Add screenshots or videos to the report to provide additional context

• Schedule the report to be gene...read more

Process is a program in execution. Synchronization is the coordination of multiple processes or threads.

• Process is a program in execution that has its own memory space and resources.

• Synchronization is the coordination of multiple processes or threads to ensure they do not interfere with each other.

• Synchronization can be achieved through various mechanisms such as locks, semaphores, and monitors.

• Examples of synchronization include ensuring only one thread accesses a shared res...read more

Recursion is a process in which a function calls itself repeatedly until a base condition is met.

• Recursion involves breaking down a problem into smaller subproblems and solving them recursively.

• It uses a stack to keep track of function calls and their parameters.

• Examples include factorial, Fibonacci sequence, and binary search.

• Compiler executes recursion by allocating memory for each function call and storing the return address and local variables on the stack.

• It then pops th...read more

Design class diagram for Flower shop

• Create a Flower class with attributes like name, color, price, etc.

• Create a Bouquet class that has a list of Flower objects

• Create a Customer class with attributes like name, address, phone number, etc.

• Create an Order class that has a Customer object and a Bouquet object

• Create a Payment class with attributes like payment method, amount, etc.

• Create a Delivery class with attributes like delivery address, delivery date, etc.

Spring MVC follows a Model-View-Controller architecture pattern for building web applications.

• Spring MVC separates the application into three main components: Model, View, and Controller.

• Model represents the data of the application and the business logic to manipulate the data.

• View is responsible for rendering the data to the user interface.

• Controller handles the user input, processes it, and interacts with the Model and View.

• Spring MVC uses DispatcherServlet as the front con...read more

Program to reverse a linked list

• Create a new empty linked list

• Traverse the original linked list and insert each node at the beginning of the new list

• Return the new reversed linked list