Xongl Cloud Web Developer Interview Questions and Answers

Design a parking lot with Logic Flow Diagram, E-R diagram, DB tables with relations, and commands for transactions.

• Identify the types of vehicles that will use the parking lot

• Determine the number of parking spaces needed for each vehicle type

• Create a flow diagram to show the process of entering and exiting the parking lot

• Design an E-R diagram to show the relationships between entities such as vehicles, parking spaces, ...read more

To find min and max of an array in one traversal, initialize min and max to first element and compare with rest.

• Initialize min and max to first element of array

• Traverse the array and compare each element with min and max

• Update min and max accordingly

• Return min and max

Given a chessboard, find the maximum number of squares present.

• Start with the smallest square and count all possible squares

• Use the formula n*(n+1)*(2n+1)/6 to find the total number of squares in an n x n chessboard

• Add up the squares of all sizes from 1 to n to get the maximum number of squares

• For example, an 8 x 8 chessboard has 204 squares

C++ is a high-level programming language used for developing system software, application software, device drivers, and video games.

• C++ was developed by Bjarne Stroustrup in 1983.

• It is an extension of the C programming language.

• C++ supports object-oriented programming, generic programming, and low-level memory manipulation.

• It is used in developing operating systems, browsers, databases, and more.

• Examples of popular sof...read more

Deep copy creates a new object with a new memory address, while shallow copy creates a new reference to the same memory address.

• Deep copy duplicates the object and all its nested objects, while shallow copy only duplicates the top-level object.

• Deep copy is slower and more memory-intensive than shallow copy.

• Shallow copy can lead to unexpected behavior if the original object is modified.

• In Python, deep copy can be achiev...read more

Preinitialization is the process of initializing data or objects before they are actually needed.

• Preinitialization can improve performance by reducing the time needed to initialize data or objects when they are actually needed.

• It can also help to avoid delays or interruptions during runtime.

• Examples of preinitialization include preloading data into memory, initializing objects in advance, and caching frequently used da

Polymorphism can be achieved through method overloading, method overriding, and interfaces. Multiple inheritance can be solved using interfaces.

• Method overloading allows multiple methods with the same name but different parameters

• Method overriding allows a subclass to provide its own implementation of a method already defined in its superclass

• Interfaces provide a way to achieve multiple inheritance by allowing a class ...read more

WAP to generate a matrix from a given tree.

• Create a 2D array to store the matrix

• Traverse the tree and fill the matrix accordingly

• Use BFS or DFS to traverse the tree

• The matrix will be symmetric along the diagonal

Primary key is a column or set of columns that uniquely identifies each row in a table. Unique key is a constraint that ensures uniqueness of values in a column or set of columns.

• Primary key is used to enforce data integrity and ensure that each row in a table can be uniquely identified.

• Unique key is used to ensure that no two rows in a table have the same values in a column or set of columns.

• Primary key can be a singl...read more

Yes, a unique key can be a primary key.

• A primary key is a unique identifier for a record in a table.

• A unique key is a constraint that ensures the values in a column are unique.

• A unique key can be used as a primary key if it meets the requirements.

• A primary key cannot have NULL values, while a unique key can have one NULL value.

Foreign key is a column in a table that refers to the primary key of another table.

• It establishes a relationship between two tables.

• It ensures referential integrity.

• It can be null, but only if it is defined as nullable.

• It helps in joining tables.

• Example: Customer table has a foreign key to the Order table's primary key.

• Example: Order table's foreign key can be null if the order has not been placed by any customer yet.

Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity.

• Normalization involves breaking down a database into smaller, more manageable tables.

• It helps to eliminate data redundancy and inconsistencies.

• Normalization ensures that each table has a primary key and that data is stored in a logical and consistent manner.

• It improves data integrity and reduces the likelihood ...read more

Normalized form is better for data consistency and scalability.

• Normalized form reduces data redundancy and ensures data consistency.

• Normalized form allows for easier scalability and maintenance.

• Single table/2 tables may be appropriate for small, simple datasets.

• Normalized form may require more complex queries to retrieve data.

• Normalized form may require more storage space due to additional tables.

• Example: Normalized fo...read more

Create a database for Indian Premier League (IPL)

• Identify entities like teams, players, matches, venues, etc.

• Create tables for each entity with relevant attributes

• Establish relationships between tables using foreign keys

• Add constraints like unique, not null, default values, etc.

• Populate tables with data from reliable sources

Query to find player with maximum runs in a match on given date and venue

• Use MAX() function to find maximum runs

• Join tables for player name, match details and runs scored

• Filter by given date and venue

• Order by runs scored and limit to 1 result

Find A-B of two sorted arrays A and B in O(m+n) time complexity.

• Create two pointers, one for each array, and compare the elements at those pointers.

• If the element in A is smaller, add it to the result array and move the A pointer forward.

• If the element in B is smaller, move the B pointer forward.

• Repeat until one of the pointers reaches the end of its array.

• Add any remaining elements in A to the result array.

• Time comple...read more

The routine should output the elements of the inorder traversal of a binary tree one by one in each call.

• Implement an inorder traversal algorithm recursively

• Use a global variable or pass a reference to keep track of the current element

• Call the routine repeatedly to get the next element in each call

Program to find minimum semesters required to complete courses with prerequisites

• Create a graph with courses as nodes and prerequisites as edges

• Use topological sorting to find the order of courses to be taken

• Calculate the minimum number of semesters based on the order obtained

• Handle cases where there are cycles in the graph