Zscaler Softech Senior Software Engineer Interview Questions and Answers

Implement a circular list

• Use a linked list where the last node points back to the first node

• Keep track of the current node for easy traversal

• Ensure proper handling of edge cases like empty list or single node

Use load balancing, caching, and scaling techniques to handle millions of requests from clients.

• Implement load balancing to distribute requests evenly across servers.

• Utilize caching mechanisms to store frequently accessed data and reduce load on servers.

• Scale horizontally by adding more servers to handle increased traffic.

• Optimize code and database queries to improve performance and reduce response times.

The best time to buy and sell stock is when the price is low to buy and high to sell, maximizing profit.

• Buy when the stock price is low and sell when it is high

• Consider market trends and analysis to predict the best time to buy and sell

• Avoid emotional decision-making and stick to a well-thought-out strategy

Creating a bar graph using array of strings

• Create an array of strings representing the data points for the bar graph

• Each string should indicate the value of the bar and its corresponding label

• Use a visualization tool or library to plot the bar graph based on the array of strings

ConcurrentHashMap allows multiple threads to access and modify the map concurrently, while SynchronizedHashMap ensures thread-safety by allowing only one thread to access the map at a time.

• ConcurrentHashMap is more efficient in scenarios with high concurrency as it allows concurrent read and write operations.

• SynchronizedHashMap is simpler to use and provides thread-safety, but can lead to performance degradation in hig...read more

Semaphores in Java are used for controlling access to a shared resource. They can be implemented using the java.util.concurrent package.

• Use the Semaphore class from the java.util.concurrent package

• Create a Semaphore object with an initial number of permits

• Use the acquire() method to acquire a permit before accessing the shared resource

• Use the release() method to release a permit after accessing the shared resource

Bitmask in Postgresql is used to store and manipulate multiple boolean values within a single integer column.

• Bitmask is a technique to represent a set of boolean flags using binary digits.

• In Postgresql, the bitwise operators (&, |, ^, ~) can be used to perform operations on bitmasks.

• To set a specific flag in a bitmask, use the bitwise OR operator (|).

• To check if a flag is set in a bitmask, use the bitwise AND operator ...read more

Swap characters from uppercase to lowercase and lowercase to uppercase in a given string.

• Iterate through each character in the string

• Check if the character is uppercase or lowercase

• Swap the case of the character using bitwise XOR operation

• Build the resulting string with the swapped characters

To create a singleton ensuring reflection does not mess up the implementation, use an enum or a private constructor with a static field.

• Use an enum to create a singleton as enums are inherently singletons and cannot be instantiated multiple times.

• Alternatively, use a private constructor with a static field to create a singleton.

• To prevent reflection from creating multiple instances, throw an exception in the constructo...read more