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Computer Science Interview Questions and Answers

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Ques 1. What is the difference between a stack and a queue?

A stack follows the Last In, First Out (LIFO) principle, while a queue follows the First In, First Out (FIFO) principle.

Example:

Stack: Undo functionality in software. Queue: Print job scheduling.

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Ques 2. Explain the concept of polymorphism in object-oriented programming.

Polymorphism allows objects of different types to be treated as objects of a common type. It includes method overloading and method overriding.

Example:

Method overloading: Same method name with different parameters. Method overriding: Subclass provides a specific implementation of a method defined in its superclass.

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Ques 3. What is the purpose of an index in a database?

An index in a database improves the speed of data retrieval operations on a database table by providing a quick lookup mechanism.

Example:

Creating an index on a 'username' column for faster search queries.

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Ques 4. Explain the term 'Big O' notation in algorithm analysis.

Big O notation is used to describe the upper bound on the growth rate of an algorithm's time complexity in the worst-case scenario.

Example:

O(n^2) for a nested loop algorithm.

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Ques 5. What is the role of a constructor in object-oriented programming?

A constructor initializes an object's state and is called when an object is created. It typically assigns values to the object's attributes.

Example:

Java constructor: 'public MyClass(int value) { this.value = value; }'

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