Morgan Stanley Software Engineer Trainee Interview Questions and Answers

Find an odd occurring number among even occurring numbers.

• Use XOR operation to cancel out even occurring numbers and get the odd occurring number.

• Iterate through the array and XOR each element with the result variable.

• The final result will be the odd occurring number.

Print the spiral order of a binary tree and matrix.

• For binary tree, use level order traversal and alternate direction for each level.

• For matrix, use four pointers to traverse in spiral order.

• Example for binary tree: 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9

• Example for matrix: 1 2 3 4 -> 8 7 6 5 -> 9 10 11 12 -> 16 15 14 13

Finding pairs in an array with a given sum.

• Iterate through the array and for each element, check if the difference between the given sum and the element exists in the array.

• Use a hash table to store the elements of the array and their indices for faster lookup.

• If there are multiple pairs with the same sum, return any one of them.

• If no pair is found, return null or an empty array.

Find total number of k element with given avg in an array in minimum time complexity.

• Use sliding window technique to traverse the array in O(n) time complexity.

• Maintain a sum variable to keep track of the sum of elements in the window.

• If the sum of elements in the window is equal to k times the given avg, increment the count.

• Move the window by subtracting the first element and adding the next element in the array.

Printing non-boundary elements of a binary tree

• Traverse the tree in any order (preorder, inorder, postorder)

• Check if the current node is not a boundary node (not the first or last node in its level)

• If it is not a boundary node, print its value

• Recursively traverse its left and right subtrees

Yes, the string class can be extended in most programming languages.

• Inheritance can be used to extend the functionality of the string class.

• By creating a new class that inherits from the string class, additional methods and properties can be added.

• Extending the string class allows for customization and adding specific functionality to strings.

• Example: In Python, the string class can be extended by creating a new class

Implicit objects in JSP are predefined objects that are available for use without any declaration or initialization.

• Implicit objects in JSP include request, response, session, application, out, config, pageContext, page, exception, and others.

• These objects provide access to various aspects of the JSP environment and can be used to perform common tasks.

• For example, the request object allows access to HTTP request parame...read more

A hash map is a data structure that uses a hash function to map keys to values.

• Hash map stores key-value pairs

• It uses a hash function to compute an index for each key

• Collisions can occur when two keys hash to the same index

• Hash maps provide fast access to values based on their keys

StringBuffer and StringBuilder are both used to manipulate strings, but StringBuffer is thread-safe while StringBuilder is not.

• StringBuffer is synchronized, making it safe for use in multi-threaded environments.

• StringBuilder is not synchronized, making it faster but not thread-safe.

• StringBuffer is preferred when multiple threads are involved, while StringBuilder is preferred for single-threaded scenarios.

• Both classes p...read more

MVC is a software architectural pattern that separates an application into three main components: Model, View, and Controller.

• Model represents the data and business logic of the application.

• View is responsible for displaying the user interface.

• Controller handles user input, updates the model, and interacts with the view.

• MVC promotes separation of concerns and modularity in software development.

• Example: In a web applica...read more

Annotations used in RESTful web services

• 1. @Path - Specifies the URI path for the resource

• 2. @GET - Specifies that the method handles HTTP GET requests

• 3. @POST - Specifies that the method handles HTTP POST requests

• 4. @PUT - Specifies that the method handles HTTP PUT requests

• 5. @DELETE - Specifies that the method handles HTTP DELETE requests

• 6. @PathParam - Binds the value of a URI template parameter to a method paramete...read more