Wissen Interview Questions and Answers

A hashmap is a data structure that stores key-value pairs for efficient data retrieval using a hash function.

• Uses an array to store data, where each index corresponds to a hash value.

• A hash function converts keys into array indices, e.g., hash('key') % array_size.

• Handles collisions using methods like chaining (linked lists) or open addressing.

• Example: Inserting ('apple', 1) and ('banana', 2) into a hashmap.

• Average...read more

Merging two sorted arrays involves combining them into a single sorted array while maintaining order.

• Two-Pointer Technique: Use two pointers to traverse both arrays, comparing elements and adding the smaller one to the result array.

• Example: For arrays [1, 3, 5] and [2, 4, 6], start with pointers at 1 and 2, add 1 to result, move pointer of first array.

• Handle Remaining Elements: After one array is fully traversed, ...read more

The four pillars of OOP are encapsulation, inheritance, polymorphism, and abstraction, forming the foundation of object-oriented programming.

• Encapsulation: Bundling data and methods that operate on the data within a single unit (class). Example: A class 'Car' with attributes like 'color' and methods like 'drive()'.

• Inheritance: Mechanism where a new class inherits properties and behavior from an existing class. Exa...read more

A flight reservation system allows users to search, book, and manage flight tickets efficiently.

• User Registration: Users can create accounts to manage bookings.

• Flight Search: Users can search flights by destination, date, and number of passengers.

• Booking Process: Users can select flights, enter passenger details, and make payments.

• Cancellation and Refund: Users can cancel bookings and request refunds as per polici...read more

Hashmap is a data structure that stores key-value pairs and provides constant time complexity for insertion, deletion, and retrieval.

• Hashmap uses a hash function to map keys to their corresponding values in an array.

• Collisions can occur when two keys map to the same index, which can be resolved using techniques like chaining or open addressing.

• Java's HashMap class is an implementation of the hashmap data structure...read more