Write a code to delete the middle element of a stack without using any additional data structure while preserving the original order. Input: [1, 2, 3, 4, 5]. Output: [1, 2, 4, 5]
WellDev Ltd
| Founding year | |
| Company Website | https://www.welldev.io/ |
| Career Website | https://www.welldev.io/careers |
| Technologies Used | Ruby on Rails, Android, iOS, ReactJS |
Introduction
WellDev Ltd is a software company based in Zurich, Switzerland, specializing in software development and IT services. It has offices in Bangladesh (Dhaka), South Africa, Canada etc.
Interview Stages
- Initial Screening: After dropping CV they take a MCQ Round, almost every candidate gets an email for participation in this round.
- Round 1: The first round is a technical round and generally lasts for an hour.
- Round 2: The second round is divided into two part. The first part is a behavioural part taken by HR of the company. For the second part two software engineer conducts the technical sessions.
- COO Round: The final round is taken by the COO of the company
MCQ Round
A Broad Range of Topics
This round consisted of a multiple-choice questionnaire covering these topics. The test required me to share my screen with Quillgo and keep my camera on. It covers wide range of topics like JavaScript fundamentals, OOP, DBMS, SWE principles, Networking, Rest API knowledge, Analytical reasoning, DSA (time complexity, sorting, binary trees, MST, greedy algorithms).
First Round Questions
Hands-On Problem Solving
What will the output of this code in C Programming Language and why?
C
int arr[3] = {1, 2, 3};
if(&arr[0] == &arr){
printf("They are the same!");
}else {
printf("Not same");
}Given an array, what will be the base address if we print the array name only (e.g., printf(ara))?
What is the time complexity of the print statement? if it's O(1) why is that? Is it the same case for Linked List? If it's not, why it isn't the same case?
python
arr = [1, 2, 3, 4]
print(arr[2])Can we run binary search on a sorted LinkedList? If we can, what issues we might face?
python
def fn(n):
if n == 0:
return 0
return n + fn(n-1)Given the above function, rename the function according to what the function tries to achive.
2nd Iteration: Write the same function but in a iterative manner. Does the both implementations have same Time Complexity and Space Complxity?
What is the time complexity of the following code?
C
int fun(int n) {
if(n <= 1) return n;
int x = fun(n - 1);
int y = fun(n - 2);
return x + y;
}Explain the order of SQL query execution (e.g., FROM, WHERE, GROUP BY, HAVING, SELECT).
Given a table with redundant data in multiple columns, how would you optimize it? (Hint: Normalization)
Given a Java code, identify issues that violate access modifiers.
Explain the basic concepts of Object-Oriented Programming (OOP).
What are the ACID properties in DBMS?
A basic GRE-like math question.
Write a SQL query to show all the duplicate rows in a table.
Can we make a stack with a queue?
Second Round Questions
Write an API call to check whether the system is running properly and explain a GET API call.
Write a code to create a directory and a text file inside it with “Hello World” written.
What happens if two people try to reserve the same ticket simultaneously in a ticket reservation system? How would you solve this problem in a ticket management system? What will be your idea in this regard?
How many APIs are required to solve the above ticket reservation problem?
How can passwords be secured so that no one (even the administrator) can view them? How can password hashing be strengthened? What techniques do you know? (Hint: Salting and hashing techniques)
What is a trigger in DBMS, and what does cascading mean?
If we need to display a large amount of data on a website, what technique should be followed? (Hint: Pagination)
What happens when we browse a website? How are the contents rendered?
What is the difference between SQL and NoSQL?
For storing values from cache memory to RAM, should we use SQL or NoSQL?
Given an array of integers heights representing the histogram's bar height where the width of each bar is 1, return the area of the largest rectangle in the histogram.
You have a n-story building, and two eggs. An egg will break if dropped from a certain height (ie above a floor f). Determine the minimum number of moves that you need to determine with certainty what the value of f is.
Given a table with product_id, price, and product_name, write a query to find products with the same price.
What is the difference between DELETE, TRUNCATE, and DROP in SQL?
Explain threading in OOP.
How do you check for changes in a database?
Many questions from my CV (all practical, not just asking what you have done).
Given an integer array nums, move all 0's to the end of it while maintaining the relative order of the non-zero elements.