What century is it in Java
The challenge
Return the century of the input year. The input will always be a 4 digit string, so there is no need for validation.
Java
345 articles about java development, tools, and best practices
Lost number in number sequence in Java
The challenge
An ordered sequence of numbers from 1 to N is given. One number might have deleted from it, then the remaining numbers were mixed. Find …
Read Article →Simple string reversal in Java
The challenge
In this challenge, we are going to reverse a string while maintaining the spaces (if any) in their original place.
For example: …
Read Article →int32 to IPv4 in Java
The challenge
Take the following IPv4 address: 128.32.10.1
This address has 4 octets where each octet is a single byte (or 8 bits).
- 1st octet
128has …
Perimeter of squares in a rectangle in Java
The challenge
The drawing shows 6 squares the sides of which have a length of 1, 1, 2, 3, 5, 8. It’s easy to see that the sum of the perimeters …
Read Article →Palindrome chain length in Java
The challenge
Number is a palindrome if it is equal to the number with digits in reversed order. For example, 5, 44, 171, 4884 are palindromes, and 43 …
String array duplicates in Java
The challenge
You are given an array of strings and your task is to remove all consecutive duplicate letters from each string in the array.
For …
Read Article →Even or Odd Array Sum in Java
The challenge
Given a list of numbers, determine whether the sum of its elements is odd or even.
Give your answer as a string matching "odd" …
String Permutations in Java
The challenge
In this challenge, you have to create all permutations of an input string and remove duplicates if present. This means you have to …
Read Article →Remove a Specific Element of an Array in Java
The challenge
You will be given a certain array of length n, such that n > 4, having positive and negative integers but there will be no zeroes and …
Upside down numbers in Java
The challenge
Consider the numbers 6969 and 9116. When you rotate them 180 degrees (upside down), these numbers remain the same. To clarify, if we …
Rotate matrix counter-clockwise N times in Java
The challenge
In this challenge your mission is to rotate matrix counter-clockwise N times.
So, you will have 2 inputs:
1) matrix
2) a number, how …Square Matrix Multiplication in Java
The challenge
Write a function that accepts two square (NxN) matrices (two dimensional arrays), and returns the product of the two. Only square …
Count the divisible numbers in Java
The challenge
Complete the function that takes 3 numbers x, y and k (where x ≤ y), and returns the number of integers within the range [x..y] (both …
Averages of numbers in Java
The challenge
Get the averages of these numbers
Write a method, that gets an array of integer-numbers and return an array of the averages of each …
Read Article →Decimal to Factorial and Back in Java
The challenge
Coding decimal numbers with factorials is a way of writing out numbers in a base system that depends on factorials, rather than powers …
Read Article →Vowel Count in Java
The challenge
Return the number (count) of vowels in the given string.
We will consider a, e, i, o, u as vowels for this challenge (but not y).
The …
Read Article →Equal Sides Of An Array in Java
The challenge
You are going to be given an array of integers. Your job is to take that array and find an index N where the sum of the integers to the …
Read Article →Largest 5 digit number in a series in Java
The challenge
In the following 6 digit number:
283910
91 is the greatest sequence of 2 consecutive digits.
In the following 10 digit number: …
Read Article →Next smaller number with the same digits in Java
The challenge
Write a function that takes a positive integer and returns the next smaller positive integer containing the same digits.
For example: …
Read Article →Count of positives / sum of negatives in Java
The challenge
Given an array of integers.
Return an array, where the first element is the count of positives numbers and the second element is sum of …
Read Article →Find the stray number in Java
The challenge
You are given an odd-length array of integers, in which all of them are the same, except for one single number.
Complete the method …
Read Article →4 By 4 Skyscrapers in Java
The challenge
In a grid of 4 by 4 squares you want to place a skyscraper in each square with only some clues:
- The height of the skyscrapers is …
How to Fix: package org.junit.jupiter.api does not exist
The problem
If you have received the package org.junit.jupiter.api deos not exist error when trying to run a JUnit Java Test with Maven, it’s …