Toptal Software Developer Interview Questions and Answers

SQL command for creating a table

• Use CREATE TABLE statement

• Specify table name and column names with data types

• Add any constraints or indexes as needed

SQL commands for inserting, updating, and deleting data from a table.

• INSERT INTO table_name (column1, column2, column3) VALUES (value1, value2, value3);

• UPDATE table_name SET column1 = new_value1 WHERE condition;

• DELETE FROM table_name WHERE condition;

Truncate and drop are SQL commands used to remove data from a table.

• Truncate removes all data from a table but keeps the structure intact.

• Drop removes the entire table and its structure.

• Truncate is faster than drop as it only removes data.

• Drop cannot be undone while truncate can be rolled back.

• Truncate resets the identity of the table while drop does not.

• Examples: TRUNCATE TABLE table_name; DROP TABLE table_name;

C++ is an extension of C with object-oriented programming features.

• C++ supports classes and objects while C does not.

• C++ has better support for polymorphism and inheritance.

• C++ has a standard template library (STL) while C does not.

• C++ allows function overloading while C does not.

• C++ has exception handling while C does not.

I am a software developer with experience in Java and Python.

• I have a Bachelor's degree in Computer Science.

• I have worked on various projects involving web development and data analysis.

• I am proficient in Java and Python programming languages.

• I have experience with frameworks such as Spring and Django.

• I am familiar with databases such as MySQL and MongoDB.

I have always been fascinated by technology and its ability to solve complex problems.

• I enjoy problem-solving and logical thinking

• I have a natural curiosity for how things work

• I see the potential for technology to make a positive impact on society

• I have experience in programming and find it rewarding

• I am excited about the constant innovation and evolution in the IT industry

My strengths include problem-solving, adaptability, and teamwork. My weakness is public speaking.

• Strengths: problem-solving, adaptability, teamwork

• Examples: I have successfully solved complex coding problems, adapted to new technologies quickly, and collaborated effectively with team members.

• Weakness: public speaking

• Examples: I get nervous when speaking in front of large groups, but I am working on improving my present

I have the technical skills, experience, and passion to excel in this role.

• I have a strong background in software development, with expertise in multiple programming languages and frameworks.

• I have experience working on complex projects and collaborating with cross-functional teams.

• I am passionate about staying up-to-date with the latest technologies and trends in the industry.

• I am a quick learner and adaptable to new ...read more

Network layers are a hierarchical way of organizing communication protocols.

• Network layers provide a modular approach to networking.

• Each layer has a specific function and communicates with adjacent layers.

• The OSI model has 7 layers, while the TCP/IP model has 4 layers.

• Examples of layers include the physical layer, data link layer, network layer, transport layer, and application layer.

Deadlock is a situation where two or more processes are unable to proceed because they are waiting for each other to release resources.

• Occurs in multi-threaded/multi-process environments

• Can lead to system freeze or crash

• Prevention techniques include resource ordering and timeouts

• Example: Process A holds resource X and waits for resource Y, while Process B holds resource Y and waits for resource X

Paging and Segmentation are memory management techniques used by operating systems.

• Paging divides memory into fixed-size pages and stores them in physical memory.

• Segmentation divides memory into logical segments and stores them in physical memory.

• Paging allows for efficient use of physical memory and reduces fragmentation.

• Segmentation allows for protection and sharing of memory between processes.

• Examples of operating s...read more

Reverse a linked list using iterative and recursive methods.

• Iterative method involves traversing the list and changing the pointers to reverse the order.

• Recursive method involves calling the function recursively on the next node and changing the pointers.

• Both methods have O(n) time complexity and O(1) space complexity.

• Example: 1->2->3->4->5 becomes 5->4->3->2->1.

Clone a linked list with a random pointer.

• Create a new node for each node in the original list.

• Use a hash table to map the original nodes to their clones.

• Iterate through the original list again and update the random pointers of the clone nodes.

The question asks to input an array and print the repeating characters.

• Iterate through the array and store each element in a hash table or dictionary.

• If an element already exists in the hash table, it is a repeating character.

• Print all the repeating characters found.

Program to find the second minimum in an array.

• Sort the array and return the second element.

• Initialize two variables to store minimum and second minimum values.

• Loop through the array and update the variables accordingly.

To find the longest palindrome in a given string.

• Iterate through the string and check for palindromes of odd and even lengths.

• Keep track of the longest palindrome found so far.

• Use two pointers to check if the substring is a palindrome.

• If the substring is a palindrome and its length is greater than the current longest palindrome, update the longest palindrome.

Find the next higher number with equal number of ones in binary representation.

• Convert input number to binary

• Count number of ones in binary representation

• Increment input number until binary representation has equal number of ones

• Convert incremented number to decimal

Find the duplicate number in an array of 10 numbers with only 2 steps.

• Use a hash set to keep track of visited numbers.

• Iterate through the array and check if the number is already in the set.

• If it is, then it is the duplicate number.

• If not, add it to the set.

• At the end, the duplicate number will be found.

Program to print elements of a linked list in reverse order using same single linked list

• Traverse the linked list and push each element onto a stack

• Pop elements from the stack and print them in reverse order

To check the occurrence and correctness of HTML tags, we can use various tools and techniques.

• One way is to use a browser's developer tools to inspect the HTML code and see the tags and their frequency.

• Another way is to use an online HTML validator tool that checks for correct syntax and tag usage.

• We can also use programming languages like Python to parse HTML and count the occurrence of each tag.

• Regular expressions ca...read more