50 Programming and Python Interview Questions You Should Know How To Answer

Edited and approved by: Stefan Bradstreet

It might be a difficult task for a novice programmer to prepare for their technical interview. This is because he/she does not know what to expect from the interviewers. This article will investigate the 50 most essential coding questions that a programmer ought to expect during their technical interview. Remember in addition to the questions the interviewer is showing how well you can verbally communicate so practice these questions privately and rehearse your answers before going to your programming interview. Also you can look into finding a mock interview coach that will give you an interview along with ask you example coding questions you may face during your interview. The mock interviewer will then give you open feedback about how you did and give you ways you can improve before your big day. I offer such services as well that you can contact me for over at the contact page. I also provide other tips about how you can prepare for your technical interview in the weeks leading up to it here.

Try to answer the questions on your own first and then check out the example answers towards the bottom of the page.

TOP 10 DATA STRUCTURE QUESTIONS

  1. What are data structures?
  2. Why are data structures important?
  3. What is hashing?
  4. How do you implement a hash table?
  5. In what situation would you use a queue over a stack?
  6. In what situation would you use a stack over a queue?
  7. What are the commonly used data structures?
  8. What are the two types of arrays?
  9. What are the primary array operations?
  10. What is a tree data structure?

TOP 10 ALGORITHM QUESTIONS

  1. How does bubble sort algorithm work?
  2. Write a summary of bubble sort complexity and performance.
  3. Which is better between bubble sort and selection sort?
  4. Which is better between bubble sort and selection sort?
  5. How do you check if a tree contains a certain value?
  6. Which is better between merge sort and quick sort?
  7. What is the time complexity of an algorithm?
  8. List the three types of notations that are used for time complexity?
  9. Explain how you can determine if a linked list has a loop or not?
  10. Give three examples of cryptographic algorithms.
  11. What is a Radix Sort Algorithm? (Bonus question)

TOP 10 OBJECT-ORIENTED QUESTIONS

  1. What are the basic concepts of OOP?
  2. What is OOPS (Operating Oriented Program System)?
  3. What is an object?
  4. What is inheritance?
  5. What is function overloading?
  6. What is the use of finalize method?
  7. What is the super keyword?
  8. What is method overriding?
  9. What are the access modifiers?
  10. What is the default access modifier in a class?

TOP 10 PYTHON SPECIFIC QUESTIONS WITH ANSWERS

  1. What is Python? What are the advantages of using Python?
  2. What are Python decorators?
  3. What is lambda in Python?
  4. What is slicing in Python?
  5. What is a pass in Python?
  6. What is namespace in Python?
  7. How can you copy an object in Python?
  8. How do you delete a file in Python?
  9. What is a negative index in Python?
  10. What are the local variables in Python?

TOP 10 BEHAVIORAL QUESTIONS

  1. What are your most significant weaknesses?
  2. What are your biggest strengths?
  3. Where do you see yourself in five years?
  4. How did you learn about the opening?
  5. Why do you want this job?
  6. Why do you want to leave your current job?
  7. What is your leadership style?
  8. The last time a customer or co-worker got angry with you. What happened?
  9. Tell me a little about yourself.
  10. What questions would you like to ask?

TOP 10 DATA STRUCTURE QUESTIONS WITH ANSWERS

1. What are data structures?

In programming, these are the structures that act as storage centers for information. They store the corresponding data in a particular format.

2. Why are data structures important?

Data structures are significant because they help in the organization and storage of data. The data is stored in specific formats according to particular situations.

3. What is hashing?

Hashing is founded on the keys distribution in an array, H [0..m-1]. This particular distribution is performed by the calculation of every single key that bears an element of a hash function h.

4. How do you implement a hash table?

Hash tables are the particular dynamic structures of data that are responsible for the implementation of associative arrays. To fathom the programming implementation of a hash table, let us check an array. An element can be accessed using its respective key, whereby there might be a case where cells contain certain aspects while there are others that don’t.

5. In what situation would you use a queue over a stack?

In programming, if you want to access things following the order that was used to arrange them, then it is advisable to use a queue over a stack.

6. In what situation would you use a stack over a queue?

a) A stack can be used while evaluating an expression

b) Use a stack while conversion of infix to postfix

c) Use a stack while doing Depth First Search (DFS)

d) Use a stack while on function calls

7. What are the commonly used data structures?

The most popular types of data structures include;

Queue

Tree

Hash Table

Graph

Array

Linked List

Stack

8. What are the two types of arrays?

1. Multidimensional arrays (arrays of arrays)

2. One dimensional array

9. What are the primary array operations?

Delete – getting rid of an item

Insert – inserting an item

Get – accessing an item

Size – finding the total amount of elements in an array

10. What is a tree in data structure?

In programming, trees are the hierarchical structures of data that constitute of edges and nodes (vertices) that connect them. Trees are a sub-type of graph where the nodes to not have edges that result in cycles.

TOP 10 ALGORITHM QUESTIONS WITH ANSWERS

1. How does bubble sort algorithm work?

Bubble sort algorithm sorts out from the smallest to the largest numbers. This depends on how one is sorting, for instance, descending or ascending, the bubbles sort from either the start or end of an array.

2. Write a summary of bubble sort complexity and performance.

Bubble sort average performance O(n^2)

Bubble sort worst performance O(n^2)

Bubble sort best performance O(n)

3. Which is better between bubble sort and selection sort?

Bubble sort performs better because it is faster in the sorting process. This is because there is a rapid movement of data for the same amount of comparisons.

4. How do you check if a tree contains a certain value?

You can do a binary or a depth search traversal of the tree and compare the node value in the traversal to the value you are looking for. If after searching the entire tree you don’t find the value then you should return a boolean False or empty string to denote the value was not in the tree.

5. Which is better between merge sort and quick sort?

Quicksort is much better because the constant accompanied by it is much lesser than that of the merge sort.

6. What is the time complexity of an algorithm?

The time complexity of an algorithm is an indicator of the time remaining for the particular algorithm to complete running. The O notation indicates time complexity.

7. List the three types of notations that are used for time complexity.

a) Big Theta; This is used to represent “the same as” <expression> iterations

b) Big Omega; This is used to represent “same as or more than” <expression> iterations

c) Big Oh; This is used to represent “the same as or fewer than” <expression> iterations

8. Explain how you can determine if a linked list has a loop or not?

The process is quite simple; first, you store a visited node in a node set. Than you check the node set for each new node you visit in the linked list and see if that node exists within that set.

9. Give three examples of cryptographic algorithms.

a) Triple-DES and DES

b) CMEA

c) GOST algorithms

10. What is a Radix Sort Algorithm?

This is a type of algorithm that is linear sorting. It works with integers and arranges elements by computing the numbers’ digits.

TOP 10 OBJECT-ORIENTED QUESTIONS WITH ANSWERS

1. What are the basic concepts of OOPS

The basic concepts of Object-Oriented Programming include;

a) Polymorphism

b) Encapsulation

c) Abstraction

d) Inheritance

2. What is OOPS?

OOPS is an abbreviation of Object-Oriented Programming System whereby every single object is an example of class, and different programs are viewed as piles of objects.

3. What is an object?

This is a class instance that bears its own identity, behavior, and state.

4. What is inheritance?

This is a concept whereby the behavior and structure of one class are defined in another. Inheritance of one class is single inheritance, while that of many classes is termed as multiple inheritances.

5. What is function overloading?

In object-oriented programming, this is a regular function that can also perform different additional tasks. It can accommodate the making of other various methods that bear the same name but differ by the type output and input of functions.

6. What is the use of finalize method?

In object-oriented programming, it helps in the performance of cleanup operations on the dormant resources. This method is protected and is accessible through a respective class or a derived class.

7. What is the super keyword?

It is used in the invocation of an overridden method and overrides its single super methods. The keyword can also allow access to overridden methods and makes the hidden members of a superclass accessible.

8. What is method overriding?

In object-oriented programming systems, this is a characteristic that ensures a subclass can enable the implementation of a method that overrides in the major class.

9. What are the access modifiers?

They determine the extent of the variables that can be accessed from several other classes or objects. The different types of access modifiers include;

Private

Protected

Public

10. What is the default access modifier in a class?

It is always private by default.

TOP 10 PYTHON SPECIFIC QUESTIONS WITH ANSWERS

1. What is Python? What are the advantages of using Python?

This is a programming language that consists of threads, automatic memory management, exceptions, modules, and objects. The advantages of Python include portability, simplicity, open-source, extensiveness, and a built-in data structure.

2. What are Python decorators?

A python decorator is an abstract function that you can use to wrap a function with another function. This allows you to easily reuse functionality by adding the syntax @decorator_function above your function. Common uses of decorators is to wrap logging, permissions checking, and debugging run-times.

3. What is lambda in Python?

A python lambda is an abstract function that you can declare inline and pass to other methods for small inline callbacks.

4. What is slicing in Python?

This is a mechanism that selects items from a sequence, for instance, lists, strings, tuples, e.t.c.

5. What is a pass in Python?

This refers to no-operation. In a compound statement, it is a place holder that shows where it should be left blank.

6. What is namespace in Python?

In Python, this is a box-like platform where a name/variable is mapped to the placed object. When the name/variable is searched, this box-like platform is retrieved and produces the corresponding result. Namespacing is assigned by the module folder name and the name of the python file.

7. How can you copy an object in Python?

For python, in the general case, you can do copy.deepcopy() or copy.copy(). Copying is needed because Python passes all objects to functions by reference which means if a function modifies an object such as a list then that same modification will happen outside the calling scope of the function.

ex_list = [0,1,2]

def change_first_element_of_list(input_list):
  input_list[0] = 3

change_first_element_of_list(ex_list)
print(ex_list)

# Outputs [3,1,2]

8. How do you delete a file in Python?

You can use the command os.unlink (filename) or os.remove (filename). You can also use shutil.rmtree(dir) for deleting entire directories.

9. What is a negative index in Python?

In a python sequence, an index can be in either positive or negative numbers where a negative index gets you the elements from the right side of a list. IE the negative index -1 would return the last element in an array.

10. What are the local variables in Python?

When a particular variable gets a new value within the respective function’s body, then it is local. There are also global and module level variables.

TOP 10 BEHAVIORAL QUESTIONS

1. What are your most significant weaknesses?

Choose a theoretical weakness and structure it into a formidable behavioral strength.

2. What are your biggest strengths?

Choose your behavioral strengths carefully and explain them precisely with examples.

3. Where do you see yourself in five years?

It is a question meant to trick you. Just combine your ambition with a genius stroke of behavioral humility.

4. How did you learn about the opening?

Explain that you heard about it from a colleague, current employer, or by following the company.

5. Why do you want this job?

Explain why the job will help you accomplish your short and long term ambitions.

6. Why do you want to leave your current job?

Don’t talk bad about your former company or colleagues. Focus on how this new job will help you grow your career.

7. What is your leadership style?

Highlight several formidable examples of behavioral situations and how you would handle them.

8. The last time a customer or co-worker got angry with you. What happened?

Don’t focus on the behavior of the blame game. Focus on how to professionally address the problem and fix it as soon as possible.

9. Tell me a little about yourself.

Articulate your likes and dislikes, strengths, and weaknesses. Be smart and coincide with the company’s needs.

10. What questions would you like to ask?

Seize the opportunity and ask your interviewers formidable and ingenious questions about themselves and the company.

Is there any other questions you think should be added to this list that you’ve ran across frequently on several interviews? Let us know in the comments!

About Stefan Bradstreet

Stefan is a software development engineer II at Amazon with 5+ years of experience in tech. He is passionate about helping people become better coders and climbing the ranks in their careers as well as his own through continued learning of leadership techniques and software best practices.


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