Senior Software Engineer 1 Interview Questions and Answers for Freshers

Use hash set to track unique elements while iterating through array and modify array in-place

• Iterate through array and add elements to hash set to track unique elements

• Modify array in-place by removing duplicates using hash set

• Return the size of the hash set as the number of unique elements

Singleton pattern ensures a class has only one instance and provides a global point of access to it.

• Create a private static instance variable of the class itself

• Make the constructor private to prevent instantiation from outside the class

• Provide a static method to access the singleton instance

An abstract class is a class that cannot be instantiated and is used as a blueprint for other classes to inherit from.

• Cannot be instantiated directly

• May contain abstract methods that must be implemented by subclasses

• Can have both abstract and non-abstract methods

• Used to define common behavior for subclasses

Check if a string of parentheses is valid

• Use a stack to keep track of opening parentheses

• Iterate through the string and push opening parentheses onto the stack

• When encountering a closing parenthesis, pop from the stack and check if it matches the corresponding opening parenthesis

• If stack is empty at the end and all parentheses have been matched, the string is valid

LRU cache design involves maintaining a cache with limited capacity and removing the least recently used item when the cache is full.

• Use a doubly linked list to keep track of the order of items in the cache.

• Implement a hash map to quickly access items in the cache.

• When an item is accessed, move it to the front of the linked list to mark it as the most recently used.

• When adding a new item to a full cache, remove the item at the end of the linked list, which is the least recent...read more