Blog Archives
1 2 3

05: Finding the 2nd highest number in an array in Java

Requirements gathering

  1. Does the array allow duplicates?
  2. If duplicates are allowed, then do you need to report duplicates? For example, in {2,4, 6, 3, 6, 5}, is 6 or 5 the second highest?


  • If duplicates are not allowed, sort the array (Arrays.sort(…)) and get the second last element, which executes in O(nlogn)
  • If duplicates are allowed, loop through each element have two variables to store highest & second highest values. which executes in O(n)

Solution: duplicates are allowed

Read more ...

08: Write code to add, subtract, multiply, and divide given numbers?

A trivial coding example (i.e. a Calculator) tackled using the following programming paradigms in Java not only to perform well in coding interviews, but also to learn these programming paradigms.

Approach 1: Procedural Programming
Approaches 2 – 4: Object Oriented Programming
Approach 5: Functional Programming (Java 8)

Approach 1: Procedural

Read more ...

20 Java coding interview questions – tips & considerations

Java coding interview questions are very common in job interviews. Good coding skills are essentials for passing the peer code reviews with flying colours. Here are 17 coding tips with Java examples. Tip #1: If you are asked to write a function or code, make sure that your code fails…

Read more ...

Fibonacci number

Q1. Can you write a function to determine the nth Fibonacci number? The Fibonacci numbers under 2000 are : 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597. Where the zeroth number being 0, first number being 1, second number being…

Read more ...

Fibonacci number with caching and Java 8 FP

Complimenting Fibonacci number coding – iterative and recursive approach, we can improve performance by caching. If you run this


and you can see “fibonacci(3)” is repeated 2 times, “fibonacci(2)” is repeated 3 times, and so on.… Read more ...

Find 2 numbers from an array that add up to the target

Q1. Given an array of integers, find two numbers such that they add up to a specific target number? For example, Given numbers: {2, 3, 8, 7, 5} Target number: 9 Result: 2 and 7 A1. Solution 1: Store processed numbers in a set.

Read more ...

Find the first non repeated character in a given string input

Firstly, understand the problem, and write down any considerations & assumptions. Next write pseudocode if that helps. Considerations 1) Pre-codnition check for null or empty input. 2) Loop through the input string, and store each “character” as a key in a map with the value being the “character count”. For…

Read more ...

Finding the missing numbers Java example

Q. Can you write code to identify missing numbers in a given array of numbers?

Solution 1: Assuming that the given numbers are in order

Read more ...

Finding the perfect number

Q. Can you write code to output the perfect number between a given range? Definition: A perfect number is a positive integer that is equal to the sum of its proper divisors. The smallest perfect number is 6, which is the sum of 1, 2, and 3. Other perfect numbers…

Read more ...

Fizz Buzz

Q1. Write a program that prints numbers from 1 to 30, but for multiples of three print “Fizz” instead of the number and for the multiples of five print “Buzz”. For numbers which are multiples of both three and five print “FizzBuzz”? A1. This is a very basic coding question,…

Read more ...

1 2 3

500+ Enterprise & Core Java programmer & architect Q&As

Java & Big Data Tutorials