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.… Read More »What century is it 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… Read More »Lost number in number sequence 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: More… Read More »Simple string reversal 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 128 has the… Read More »int32 to IPv4 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… Read More »Perimeter of squares in a rectangle 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, 194, 4773 are not. Write a… Read More »Palindrome chain length 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.… Read More »String array duplicates 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” or “even”.… Read More »Even or Odd Array Sum 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 More »String Permutations 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… Read More »Remove a Specific Element of an Array 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 write them down on a… Read More »Upside down numbers in Java

The challenge In this challenge your mission is to rotate matrix counter-clockwise N times. So, you will have 2 inputs: And the output is turned… Read More »Rotate matrix counter-clockwise N times 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 matrices will… Read More »Square Matrix Multiplication 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 ends included)… Read More »Count the divisible 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… Read More »Averages of numbers 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 More »Decimal to Factorial and Back 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).… Read More »Vowel Count 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… Read More »Equal Sides Of An Array in Java

The challenge In the following 6 digit number: 91 is the greatest sequence of 2 consecutive digits. In the following 10 digit number: 67890 is the greatest… Read More »Largest 5 digit number in a series 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: Return -1… Read More »Next smaller number with the same digits 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… Read More »Count of positives / sum of negatives 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 which… Read More »Find the stray number 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… Read More »4 By 4 Skyscrapers in Java