VMware | MST-4 | Senior Lead Engineer | All Rounds(Team 1) | Jan end 2021

Given a string of parentheses, return the number of braces required to be inserted to make the parentheses valid. Example: ()))(( -> 4 (because ()()()()()), ((())) -> 0. Note: () is valid but )( is invalid. Similar to LeetCode's Score of Parentheses.

Given an array of integers and a target sum k, find a pair of elements in the array that sum up to k. If using a map approach, handle duplicate elements. Example: I/p: 1, 2,5, 4, 3 K=7 -> O/p: 2,5. I/p 2 : 3, 4, 1 k=6 -> Output: empty. I/p 3: 3, 2, 4, 3, 1, 3 k=6 -> O/p: 3,3. Similar to LeetCode's Two Sum.

Given a binary tree, print all peripheral nodes (boundary nodes) of the tree in clockwise order.

			4
         /   \
        6     9
      /  \     \
     3    1     0
    / \    \   /  \
   4   2    4 8   3
       /         /
      5         7
                 \
                  1
                   \
                    2

Expected Output: 4,3,6,4,9,0,3,7,8,4,5. Similar to LeetCode's Boundary of Binary Tree.

Given a default index array (0,1,2,3,4,5,6,7,...) and an int[] array where int[i] gives the next index. Find a cycle and print the node count within that cycle. Examples: int[]-> 2,4,4,5,0,8,9,6 -> 3, int[]-> 2,4,4,5,5,6,2,6 -> 4.

Explain what lambda expressions are and how to write them in Java.

Discuss Java Streaming API, including what streaming is and its different types.

Given an integer array, write a method to return the count of even and odd integers using Java Lambda expressions or the Streaming API.

Explain the difference between float and double data types in Java.

Discuss the backend logic for implementing a fund switch system. Specifically, would you handle it in one transaction or two?

For handling multiple transactions, would you process them in parallel or one by one?

Design a Vending Machine with the following user roles:

• Operator: Refill Vending Machine, Take Money
• Administrator: Control Vending Machine Administrative Tasks (e.g., Product Management, Machine Configuration like Products Supported, Money), User Roles/Password
• End User (Customer): View Product, Select Product, Buy. Methods to Accept Money From End User, Perform Validation and Return Back Amount (if applicable).

Primary Requirements:

• Should support RBAC Validation.
• Support Administrator Functions like Product Management, Money Control, RBAC.
• Support End User functions (Allow User to View Product, Select Product and Buy - Method To Accept Money From End User, Perform Validation and Return Back Amount if applicable).

Secondary Requirements:

• How to extend this to support Multiple User Roles, Product, and Currency.
• NFRs like Scale.
• How to Manage Vending Machine Configuration from a Central Location (Configuration Like - Products Supported, Current Availability, State).

Discuss the Usage of SOLID Principles and Design Patterns.

How to write Many-to-Many annotations in JPA. Provide end-to-end code for JPA with a Many-to-Many relation, specifically for multiple students selecting multiple subjects. The candidate mentions keeping it simple with a relation table rather than using Many-to-Many relation annotation usage directly.

Discussion on authentication and authorization. What do you pass to validate a request (e.g., username/password/token)? How do you assure that an incoming request is a valid request?

Given a Spring Boot code snippet:

@Component
Interface I1
class A implements I1
Class B implements I2
main() {
@Autowired
I1 i;
//Will this compile, if not then what can make this work
//Requirement is to inject only class A

The expected solution is to achieve this through @Inject on the class level.

Given two sorted arrays, a and b.

a = 10, 11, 22
b = 6, 8, 12, 24

The task is to form combinations adhering to these rules:

• Both arrays are sorted.
• First element should be from A.
• Last element should be from B.
• Combination should be in ascending order.
• Elements have to be subsequent from each array.

Expected Output:

10, 12
10, 12, 22, 24
10, 24

11, 12
11, 12, 22, 24
11, 24
22, 24