The Doon School Interview Questions and Answers

Binary Search Tree is a data structure where each node has at most two children, with left child smaller and right child larger. Time complexity is O(log n) for search, insert, and delete operations.

• Nodes have at most two children - left child is smaller, right child is larger

• Search, insert, and delete operations have time complexity of O(log n)

• Example: In a BST, if we search for a value, we can eliminate half of the remaining nodes at each step

Array is a fixed-size data structure while linked list is a dynamic data structure. ArrayList and LinkedList are implementations of List interface in Java.

• Array is a contiguous block of memory with fixed size, while linked list is a collection of nodes where each node points to the next node.

• ArrayList in Java is implemented using an array, which can dynamically resize itself. LinkedList is implemented using nodes with references to the next and previous nodes.

• Arrays are faste...read more

Quick sort and Merge sort are popular sorting algorithms used to efficiently sort arrays of elements.

• Quick sort: Divide and conquer algorithm, picks a pivot element and partitions the array around the pivot. Recursively sorts subarrays.

• Merge sort: Divide and conquer algorithm, divides the array into two halves, recursively sorts the halves, and then merges them back together.

• Example: Quick sort - [3, 6, 8, 10, 1, 2, 1], Merge sort - [7, 2, 4, 1, 5, 3]

Implementation of a linked list in code format

• Define a Node class with data and next pointer

• Create LinkedList class with methods like insert, delete, search

• Handle edge cases like empty list, inserting at beginning/end

Interface defines only method signatures while abstract class can have method implementations.

• Interface cannot have method implementations, only method signatures

• Abstract class can have method implementations along with abstract methods

• A class can implement multiple interfaces but can only inherit from one abstract class

• Interfaces are used to achieve multiple inheritance in Java

• Abstract classes can have constructors while interfaces cannot

Polymorphism is the ability of a single function or method to operate on different types of data.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• There are two types of polymorphism: compile-time (method overloading) and runtime (method overriding).

• Example: a superclass Animal with subclasses Dog and Cat. Both Dog and Cat can be treated as Animals.