Simple number sequence in Java
The challenge
You are given a string of numbers in sequence and your task will be to return the missing number. If there is no number missing or there …
Read Article →Technical Articles
In-depth guides, insights, and best practices for modern software engineering
Roman Numerals Encoder in Java
The challenge
Create a function taking a positive integer as its parameter and returning a string containing the Roman Numeral representation of that …
Read Article →First Variation on Caesar Cipher in Java
The challenge
The action of a Caesar cipher is to replace each plaintext letter (plaintext letters are from ‘a’ to ‘z’ or from ‘A’ …
Read Article →Century From Year in Java
The challenge
The first century spans from the year 1 up to and including the year 100, The second – from the year 101 up to and including the year …
Read Article →Find the Smallest Number in Java
The challenge
You have a positive number n consisting of digits. You can do at most one operation: Choosing the index of a digit in the number, remove …
Convert Array to Tree in Java
The challenge
You are given a non-null array of integers. Implement the method arrayToTree which creates a binary tree from its values in accordance …
Read Article →Common Denominators in Java
The challenge
You will have a list of rationals in the form
{ {numer_1, denom_1} , ... {numer_n, denom_n} }
or
[ [numer_1, denom_1] , ... [numer_n, …Primes in Numbers in Java
The challenge
Given a positive number n > 1 find the prime factor decomposition of n. The result will be a string with the following form : …
Read Article →Maximum subarray sum in Java
The challenge
The maximum sum subarray problem consists in finding the maximum sum of a contiguous subsequence in an array or list of integers: …
Read Article →Validate Credit Card Number in Java
The challenge
Let’s implement the Luhn Algorithm, which is used to help validate credit card numbers.
Given a positive integer of up to 16 …
Read Article →Find the unique number using Java
The challenge
There is an array with some numbers. All numbers are equal except for one. Try to find it!
Solution.findUniq(new double[]{ 1, 1, 1, 2, …Find The Parity Outlier in Java
The challenge
You are given an array (which will have a length of at least 3, but could be very large) containing integers. The array is either …
Read Article →Find the missing letter using Java
The challenge
Write a method that takes an array of consecutive (increasing) letters as input and that returns the missing letter in the array.
You …
Read Article →Determine the order of braces is valid using Java
The challenge
Write a function that takes a string of braces, and determines if the order of the braces is valid. It should return true if the string …
[Solved] PKIX path building failed: unable to find valid certification path to requested target
The problem
It may happen to you that when you try and pull some Java dependencies, you will get the annoying PKIX path building failed: …
How to Find the odd int in Java
The challenge
Given an array of integers, find the one that appears an odd number of times.
There will always be only one integer that appears an odd …
Read Article →Count the number of Duplicates in Java
The challenge
Write a function that will return the count of distinct case-insensitive alphabetic characters and numeric digits that occur more than …
Read Article →Calculating Simple Max Digit Sum in Java
The challenge
In this challenge, you will be given an integer n and your task will be to return the largest integer that is <= n and has the …
The String Combat Challenge in Java
The challenge
After a long conflict, the rulers of Nek and Glo have decided that a final duel should decide the fate of their countries. Each ruler …
Read Article →Solving Single Word Pig Latin in Java
The challenge
Pig Latin is an English language game where the goal is to hide the meaning of a word from people not aware of the rules.
So, the goal …
Read Article →Count the Days in Java
The challenge
Little Annie is very excited for upcoming events. She want’s to know how many days she have to wait for a specific event.
Your job …
Read Article →Java HashMap Create or Increment Value
If you are using a HashMap to keep a running total of a series of elements, then you often need to increment a HashMap item, but if it doesn’t …
Get the Strongest even number in an interval in Java
The challenge
A strongness of an even number is the number of times we can successively divide by 2 until we reach an odd number starting with an even …
Read Article →What time is it? in Java
The challenge
How many times have we been asked this simple question in our daily lives by family, friends and strangers alike?
In this challenge you …
Read Article →