Top 10 Coding Interview Tips and some Programming Questions to get a Software Developer Job in 2020 by@javinpaul

October 14th 2019 8,975 reads

I am Java programmer, blogger on http://javarevisited.blogspot.com and http://java67.com

Coding Interviews are such an important thing in a programmer's life

that he just can't get away with that. It's the first hurdle they need

to cross to get the software developer job they wish throughout their

school and college days.

To make the matter worse, you will find that so many people on the

internet telling that coding interview is flawed, the hiring process for

programmers sucks and so on but you don't need to pay attention to

them, not at least at the start of your career.

They may be right but they are inside the train which you are trying

to get into. No matter, how much they criticize the coding interviews

and programmers' hiring process, many of them have gone through the same route to where they are.

We all know that Coding Interview System is not perfect and many are

trying to change it but until it's changed, you got to follow its rules

to get into the System. This is something for experience developers to

deal with, as a junior developer your priority should be to clear the

coding interview and get the job you want.

As an authorof a Java blog and a Medium publication, I receive a lot of queries related to coding problems and how to deal with them and that's why I keep writing articles like this which have elped a lot of programmers directly and in-directly in their career.

In this article, I am going to share with you *top 101 coding interview problems from programming job interviews* which every programmer should know.

Now that, I have cleared the confusion that Coding Interview is

important and you should not distract, let's get into real work. The big

question is *what to prepare for Coding interviews?*

Well, the most important thing to prepare is Data Structure-based coding problems like array-based coding problems, string problems, linked list problems, binary tree problems, system design problems etc.

Apart from data structure-based questions, most of the programming

job interviews also ask algorithm, design, bit manipulation, and general

logic-based questions, which I'll describe in this section.

It's important that you practice these concepts because sometimes

they become tricky to solve in the actual interview. Having practiced

them before not only makes you familiar with them but also gives you

more confidence in explaining the solution to the interviewer.

One of the main problems with coding problems is that there are

hundreds and thousands of coding problems on interviews, there are even

sites like LeetCode, HackerRank, Codewars, Topcoder, freeCodeCamp, HackerEarth which train programmers for coding interviews with lots of tough questions, which sometimes just overwhelms a beginner looking for a job.

I believe in simplicity and the 10% of effort which produces 90% of

results and that's why I have collected top 101 coding problems which

are not too tough and also frequently asked on real interviews.

Solving these problems not only gives you confidence but also help

you to recognize some of the most common algorithmic patterns which will also help you to solve some unseen problems on real interviews.

The selection of good resources is very important for success in your

coding interviews. If you chose a wrong resource then more than money,

you will lose valuable time you need for preparation, hence spend some

time researching for good resources.

If you need recommendations, following are some of my the tried and

tested resources to learn Data Structure and Algorithms in-depth for

coding interviews:

**Data Structures and Algorithms: Deep Dive Using Java**

for Java developers. Learn about Arrays, Linked Lists, Trees,

Hashtables, Stacks, Queues, Heaps, Sort algorithms and Search algorithms

**Algorithms and Data Structures in Python** for those who love Python\

A guide to implementing the most up to date algorithms from scratch: arrays, linked lists, graph algorithms, and sorting

**JavaScript Algorithms and Data Structures Masterclass**by Colt_Steele

for JavaScript programmers. The Missing Computer Science and Coding

Interview Bootcamp. Learn everything you need to ace difficult coding

interviews.

**Mastering Data Structures & Algorithms using C and C++** for those who are good at C/C++

**Data Structures in Java: An Interview Refresher** **by** **The Educative Team** to refresh important Data Structure and algorithms concepts in Java. This course contains a detailed review of all the common data structures and provides implementation level details in Java to allow readers to become well equipped.

**Grokking the Coding Interview: Patterns for Coding Questions**

Coding interviews are getting harder. The sheer number of practice questions and prep resources is growing everyday, and trying to keep up can feel overwhelming.

The struggle of trying to solve hundreds of Leetcode questions and remember what you learned from each is something familiar to many developers.

However, from my experience, what helps the most when solving interview questions is to understand the underlying patterns behind coding problems and that's where this course helps. It will train you in 15 essential coding patterns which will help you to solve hundreds of problems.

This is like the meta course for coding interviews, which will not

teach you how to solve a coding problem but, instead, teach you how to

solve a particular type of coding problems using patterns. Master these

15 underlying patterns to interview questions, and you'll be able to

tackle anything you face on the interview

And, if you prefer books, there is no better than the **Cracking The Coding Interview****, by** **Gayle Laakmann McDowell**which presents **189+ Programming questions and solution. **

A good book to prepare for programming job interviews in a short time. Btw, I will also earn some money if you buy any of these resources mentioned here.

There is no better way to do well in Coding interviews than

practicing as many coding problems as possible. This will not only train

your mind to recognize algorithmic patterns in problems but also give

you the much-needed confidence to solve the problem you have never seen before.

My second tips are to learn about as many data structure and

algorithms as possible. This is an extension of the previous tip but it

also involves reading and not just practicing. For example, If you know

about the hash table you can also many array and counter-based problems easily. Same is true for tree and graph.

Choosing the right data structure is a very important part of

software development and coding interview and unless and until you know

them, you won't be able to choose.

Time yourself --- candidates who solve interview problems within

the time limit and quickly are more likely to do well in the interview

so you should also time yourself.

Think of edge cases and run your code through them. Some good

edge cases might be the empty input, some weird input or some really

large input to test the boundary conditions and limits.

After solving the problem, try explaining it to a friend or colleagues how is also interested in coding problems. This will tell you whether you have really understood the problem or not. ** If you can explain easily means you understood**.

Also, the discussion makes your mind work and you could come up with an alternative solution and able to find some flaws in your existing algorithms.

Another useful tip to excel Coding interviews is to **appear in the coding interview and lots of them.**

You will find yourself getting better after every interview and this also helps you to get multiple offers which further allows you to better negotiate and get those extra 30K to 50K which you generally leave on a

table if you just have one offer in hand.

Btw, If you are ready for Coding Interview then you can also take **TripleByte's quiz** and go directly to the final round of interviews with top tech companies like Coursera, Adobe Acrobat, Dropbox, Grammarly, Uber, Quora, Evernote, Twitch, and many more.

I didn't know about Triplebyte before, but they are providing a great service to job seekers. A big thanks to them.

Without wasting any more of your time, here is my list of 101

frequently asked coding problems from programming job interviews. In

order to get most of this list, I suggest to actually solve the problem.

Do it yourself, no matter whether you stuck because that's the only

way to learn. After solving a couple of problems you will gain

confidence. I also suggest you look at the solution when you stuck or

after you have solved the problem, this way you learn to compare

different solution and how to approach a problem from a different angle.

**How is a bubble sort algorithm implemented? (****solution****)**

**How is a merge sort algorithm implemented? (****solution****)**

**How do you count the occurrence of a given character in a string? (****solution****)**

**How do you print the first non-repeated character from a string? (****solution****)**

**How do you convert a given String into int like the atoi()**? (**solution**) **How do you implement a bucket sort algorithm? (****solution****)**

**How do you implement a counting sort algorithm? (****solution****)**

**How do you remove duplicates from an array in place? (****solution****)**

**How do you reverse an array in place in Java? (****solution****)**

**How are duplicates removed from an array without using any library? (****solution****)**

**How is a radix sort algorithm implemented? (****solution****)**

**How do you swap two numbers without using the third variable? (****solution****)**

**How do you check if two rectangles overlap with each other? (****solution****)**

**How do you design a vending machine? (****solution****)**

**How do you find the missing number in a given integer array of 1 to 101? (****solution****)**

**How do you find the duplicate number on a given integer array? (****solution****)**

**How do you find duplicate numbers in an array if it contains multiple duplicates? (****solution****)**

**Difference between a stable and unstable sorting algorithm?** (answer)

**How is an iterative quicksort algorithm implemented? (****solution****)**

**How do you find the largest and smallest number in an unsorted integer array? (****solution****)**

**How do you reverse a linked list in place? (solution)**

**How to add an element at the middle of the linked list? (solution)**

**How do you sort a linked list in Java? (****solution****)**

**How do you find all pairs of an integer array whose sum is equal to a given number? (****solution****)**

**How do you implement an insertion sort algorithm? (****solution****)**

**How are duplicates removed from a given array in Java? (****solution****)**

**how to remove the duplicate character from String? (****solution****)**

**How to find the maximum occurring character in given String? (****solution****)**

**How is an integer array sorted in place using the quicksort algorithm? (****solution****)**

**How do you reverse a given string in place? (****solution****)**

**How do you print duplicate characters from a string? (****solution****)**

**How do you check if two strings are anagrams of each other? (****solution****)**

**How do you find all the permutations of a string? (****solution****)**

**How can a given string be reversed using recursion? (****solution****)**

**How do you check if a given string is a palindrome? (****solution****)**

**How do you find the length of the longest substring without repeating characters? (solution)**

**Given string str, How do you find the longest palindromic substring in str? (solution)**

**How do you check if a string contains only digits? (****solution****)**

**How to remove Nth Node from the end of a linked list? (****solution****)**

**How to merge two sorted linked list? (solution)**

**How to convert a sorted list to a binary search tree? (****solution****)**

**How do you find duplicate characters in a given string? (****solution****)**

**How do you count a number of vowels and consonants in a given string? (****solution****)**

**How do you reverse words in a given sentence without using any library method? (****solution****)**

**How do you check if two strings are a rotation of each other? (****solution****)**

**How to convert a byte array to String? (****solution****)**

**How do you remove a given character from String? (****solution****)**

**How do you find the middle element of a singly linked list in one pass? (****solution****)**

**How do you check if a given linked list contains a cycle? **

**How do you find the starting node of the cycle? (****solution****)**

**How do you reverse a linked list? (****solution****)**

**How do you reverse a singly linked list without recursion? (****solution****)**

**How are duplicate nodes removed in an unsorted linked list? (****solution****)**

**How do you find the length of a singly linked list? (****solution****)**

**How do you find the third node from the end in a singly linked list? (****solution****)**

**How do you find the sum of two linked lists using Stack? (****solution****)**

**What is the difference between array and linked list? (****answer****)**

**How to remove duplicates from a sorted linked list? (****solution****)**

**How to find the node at which the intersection of two singly linked lists begins. (****solution****)**

**Given a linked list and a value ***x***, partition it such that all nodes less than ***x*** come before nodes greater than or equal to ***x***. (****solution****)**

**How to check if a given linked list is a palindrome? (solution)**

**How to remove all elements from a linked list of integers which matches with given value? (solution)**

**How is a binary search tree implemented? (****solution****)**

**How do you perform preorder traversal in a given binary tree? (****solution****)**

**How do you traverse a given binary tree in preorder without recursion? (****solution****)**

**How do you perform an inorder traversal in a given binary tree? (****solution****)**

**How do you print all nodes of a given binary tree using inorder traversal without recursion? (****solution****)**

**How do you implement a postorder traversal algorithm? (****solution****)**

**How do you traverse a binary tree in postorder traversal without recursion? (****solution****)**

**How are all leaves of a binary search tree printed? (****solution****)**

**How do you count a number of leaf nodes in a given binary tree? (****solution****)**

**How do you perform a binary search in a given array? (****solution****)**

**How to Swap two numbers without using the third variable? (****solution****)**

**How to check if two rectangles overlap with each other? (****solution****)**

**How to design a Vending Machine? (****solution****)**

**How to implement an LRU Cache in your favorite programming language? (****solution****)**

**How to check if a given number is a Palindrome? (****solution****)**

**How to check if a given number is an Armstrong number? (****solution****)**

**How to find all prime factors of a given number? (****solution****)**

**How to check if a given number is positive or negative in Java? (****solution****)**

**How to find the largest prime factor of a given integral number? (****solution****)**

**How to print all prime numbers up to a given number? (****solution****)How to print Floyd's triangle? (****solution****)**

**How to print Pascal's triangle? (****solution****)**

**How to calculate the square root of a given number? (****solution****)**

**How to check if the given number is a prime number? (****solution****)**

**How to add two numbers without using the plus operator in Java? (****solution****)**

**How to check if a given number is even/odd without using Arithmetic operator? (****solution****)**

**How to print a given Pyramid structure? (****solution****)**

**How to find the highest repeating world from a given file in Java? (****solution****)**

**How to reverse given Integer in Java? (****solution****)**

**How to convert a decimal number to binary in Java? (****solution****)**

**How to check if a given year is a leap year in Java? (****solution****)**

**Can you implement a Binary search Algorithm without recursion? (****solution****)**

**Difference between a stable and unstable sorting algorithm? (****answer****)**

**What is Depth First Search Algorithm for a binary tree? (solution)**

**How is an iterative quicksort algorithm implemented? (****solution****)**

**How do you implement an insertion sort algorithm? (****solution****)**

**How is a merge sort algorithm implemented? (****solution****)**

**What is the difference between Comparison and Non-Comparison Sorting Algorithms? (****answer****)**

**How do implement Sieve of Eratosthenes Algorithms for Prime Number? (****solution****)**

**How to find sub array with maximum sum? (****solution****)**

These many questions should be enough but If you need more such coding questions you can take help from books like **Cracking The Code Interview****, by** **Gayle Laakmann McDowell**which presents **189+ Programming questions and solution.** A good book to prepare for programming job interviews in a short time.

Now, You're Ready for the Coding Interview

These are some of the most common questions outside of data structure

and algorithms that help you to do really well in your interview.

I have also shared a lot of these questions on my blog, so if you are really interested, you can always go there and search for them.

These **common coding, data structure, and algorithm questions** are the ones you need to know to successfully interview with any company, big or small, for any level of programming job.

If you are looking for a programming or software development job in

2019, you can start your preparation with this list of coding questions

and if you ready for Interview then you can also take **TripleByte's quiz**

and go directly to the final round of interviews with top tech

companies like **Coursera**, Adobe, Dropbox, Grammarly, and many more.

This list provides good topics to prepare and also helps assess your

preparation to find out your areas of strength and weakness.

Good knowledge of data structure and algorithms is important for

success in coding interviews and that's where you should focus most of

your attention.

**Further Learning**

Data Structures and Algorithms: Deep Dive Using Java

10 Books to Prepare Technical Programming/Coding Job Interviews

10 Algorithm Books Every Programmer Should Read

Top 5 Data Structure and Algorithm Books for Java Developers

From 0 to 1: Data Structures & Algorithms in Java

Data Structure and Algorithms Analysis --- Job Interview

20+ String based coding problems from interviews

20+ linked list problems from interviews

20+ basic algorithms based problems from interviews

Closing Notes

Thanks, You made it to the end of the article ... Good luck with your programming interview! It's certainly not going to be easy, but by

following this searching and sorting algorithm questions, you are one

step closer than others.

By the way, the more questions you solve in practice, the better your preparation will be.

So, if you think 101 coding problems are not enough and you need more, then check out these additional **50 programming questions** for telephone interviews and these books and courses for more thorough preparation.

All the best for your coding interview.

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