Software Engineer

Approach :

1) We can store the frequency of every element in the array in a hashmap.


2) We will loop over every index i, and check the frequency of (Target - ARR[i]) is the hashmap:
2.1) If (Target - ARR[i]) is equal to ARR[i], we will check if frequency of ARR[i] . If it is greater than 1 then we will
decrease the frequency of ARR[i] by 2 and add a pair (ARR[i] , ARR[i]) to our answer.

2.2) Else, if the frequency of ARR[i] and Target - ARR[i] is greater than equal to 1 then we add pair (ARR[i], Target -
ARR[i]) to our answer and decrease the frequency of both by 1.


3) If no valid pairs exist, we will return [[-1,-1]].


TC : O(N) , where N = size of the array
SC : O(N)

Approach :

1) Calculate the length of both the lists, say len1 and len2

2) Get the absolute difference of the lengths, diff = |len1 – len2|

3) Now traverse the long list from the first node till ‘diff’ nodes so that from there onwards both the lists have equal
number of nodes

4) Then traverse both the lists in parallel and check whether a common node is reached (Note that getting a common
node is done by comparing the address of the nodes, not the data)
4.1) If yes, return that node’s data
4.2) If no, return -1


TC : O(N) , where N = max length of the linked list
SC : O(1)

The super keyword is used to access hidden fields and overridden methods or attributes of the parent class.

Following are the cases when this keyword can be used :

1) Accessing data members of parent class when the member names of the class and its child subclasses are same.
2) To call the default and parameterized constructor of the parent class inside the child class.
3) Accessing the parent class methods when the child classes have overridden them.

1) Data Encapsulation is an Object-Oriented Programming concept of hiding the data attributes and their behaviors in
a single unit.

2) It helps developers to follow modularity while developing software by ensuring that each object is independent of
other objects by having its own methods, attributes, and functionalities.

3) It is used for the security of the private properties of an object and hence serves the purpose of data hiding.

JIT Compiler :

1) JIT stands for Just-In-Time and it is used for improving the performance during run time. It does the task of
compiling parts of byte code having similar functionality at the same time thereby reducing the amount of compilation
time for the code to run.

2) The compiler is nothing but a translator of source code to machine-executable code.


Working of JIT Compiler :

1) First, the Java source code (.java) conversion to byte code (.class) occurs with the help of the javac compiler.

2) Then, the .class files are loaded at run time by JVM and with the help of an interpreter, these are converted to
machine understandable code.

3) JIT compiler is a part of JVM. When the JIT compiler is enabled, the JVM analyzes the method calls in the .class
files and compiles them to get more efficient and native code. It also ensures that the prioritized method calls are
optimized.

4) Once the above step is done, the JVM executes the optimized code directly instead of interpreting the code again.
This increases the performance and speed of the execution.

In Java, the final keyword is used as defining something as constant /final and represents the non-access modifier.

1) final variable :
1.1) When a variable is declared as final in Java, the value can’t be modified once it has been assigned.

1.2) If any value has not been assigned to that variable, then it can be assigned only by the constructor of the class.


2) final method :
2.1) A method declared as final cannot be overridden by its children's classes.

2.2) A constructor cannot be marked as final because whenever a class is inherited, the constructors are not
inherited. Hence, marking it final doesn't make sense. Java throws compilation error saying - modifier final not
allowed here


3) final class :
3.1) No classes can be inherited from the class declared as final. But that final class can extend other classes for its
usage.

Approach :

1) Take the starting position of the rat as (0, 0) and start traversing the valid cells (which are unblocked, i.e. with value 1) through adjacent cells in the following order Down -> Left -> Right -> Up so that we can automatically get sorted
paths in alphabetical order.

2) Create another matrix/grid called ‘VISITED’ to keep track of all visited and unvisited cells

3) Recursively look for the valid set of paths possible from the starting cell until we reach the destination or an invalid
cell. We keep setting the respective ‘VISITED’ matrix/grid value of the cell to true. I.e.:-

4) If the move is possible, then move to that cell while storing the character corresponding to the move, i.e. either (D,
L, R, U) and recursively start looking for a valid move until the destination (i.e. (n - 1, n - 1)) is reached by the rat.

5) Keep marking the cells as visited. When all the paths possible are traversed from that cell, unmark that cell for
other different paths and remove the character from the path formed.

6) As soon as the last index of the grid(bottom right), our destination is reached, we store the traversed path
information in a vector/list.


TC : O(3^(N^2)), where N is the dimension of the square matrix.
SC : O(N^2)

ACID properties is the combination of Atomicity, Consistency, Isolation, and Durability properties. These properties
are very helpful in allowing a safe and secure way of sharing the data among multiple users.

1) Atomicity: This is based on the concept of “either all or nothing” which basically means that if any update occurs
inside the database then that update should either be available to all the others beyond user and application program
or it should not be available to anyone beyond the user and application program.

2) Consistency: This ensures that the consistency is maintained in the database before or after any transaction that
takes place inside the database.

3) Isolation: As the name itself suggests, this property states that each transaction that occurs is in isolation with
others i.e. a transaction which has started but not yet completed should be in isolation with others so that the other
transaction does not get impacted with this transaction.

4) Durability: This property states that the data should always be in a durable state i.e. any data which is in the
committed state should be available in the same state even if any failure or restart occurs in the system.

There are 4 types of SQL Joins : 

1) Inner Join: This type of join is used to fetch the data among the tables which are common in both the tables.

2) Left Join: This returns all the rows from the table which is on the left side of the join but only the matching rows
from the table which is on the right side of the join.

3) Right Join: This returns all the rows from the table which is on the right side of the join but only the matching rows
from the table which is on the left side of the join.

4) Full Join: This returns the rows from all the tables on which the join condition has put and the rows which do not
match hold null values.

Constraints are used to specify the rules concerning data in the table. It can be applied for single or multiple fields in
an SQL table during the creation of the table or after creating using the ALTER TABLE command. The constraints are :

1) NOT NULL - Restricts NULL value from being inserted into a column.

2) CHECK - Verifies that all values in a field satisfy a condition.

3) DEFAULT - Automatically assigns a default value if no value has been specified for the field.

4) UNIQUE - Ensures unique values to be inserted into the field.

5) INDEX - Indexes a field providing faster retrieval of records.

6) PRIMARY KEY - Uniquely identifies each record in a table.

7) FOREIGN KEY - Ensures referential integrity for a record in another table.

SELECT A.ID_Name, B.ID_Name
FROM A
INNER JOIN B ON A.ID=B.ID;

Tip 1 : Prepare the points that you will speak in your introduction prior to the interview.
Tip 2 : Tell about your current cgpa, achievements and authenticated certification
Tip 3 : I told about my role in current internship and what all I do

Tip 1 : The cross questioning can go intense some time, think before you speak.

Tip 2 : Be open minded and answer whatever you are thinking, in these rounds I feel it is important to have opinion.

Tip 3 : Context of questions can be switched, pay attention to the details. It is okay to ask questions in these round,
like what are the projects currently the company is investing, which team you are mentoring. How all is the work
environment etc.

Tip 4 : Since everybody in the interview panel is from tech background, here too you can expect some technical
questions. No coding in most of the cases but some discussions over the design can surely happen.