Java

The challenge Take an integer n (n >= 0) and a digit d (0 <= d <= 9) as an integer. Square all numbers k (0 <= k <= n) between… Read More »Count the Digit in Java

The challenge Create a function multiplyAll/multiply_all which takes an array of integers as an argument. This function must return another function, which takes a single integer as… Read More »Multiply all elements in an array in Java

The challenge Usually when you buy something, you’re asked whether your credit card number, phone number or answer to your most secret question is still… Read More »Credit Card Mask in Java

The challenge Given a number, write a function to output its reverse digits. (e.g. given 123 the answer is 321) Numbers should preserve their sign;… Read More »How to Reverse a Number in Java

The challenge Suppose you have 4 numbers: ‘0’, ‘9’, ‘6’, ‘4’ and 3 strings composed with them: Compare s1 and s2 to see how many positions they have in common: 0 at index… Read More »Positions Average in Java

The challenge What date corresponds to the nth day of the year?The answer depends on whether the year is a leap year or not. Write a function… Read More »Determine the Date by the Day Number in Java

The challenge You have to create a method, that corrects a given time string. There was a problem in addition, so many of the time… Read More »Correct the time-string in Java

The challenge You probably know that some characters written on a piece of paper, after turning this sheet 180 degrees, can be read, although sometimes… Read More »Shifter Words Challenge in Java

The challenge Make two functions, max and min that take a(n) array/vector of integers list as input and outputs, respectively, the largest and lowest number in that array/vector. Examples Additionally… Read More »Find Maximum and Minimum Values of a List in Java

The challenge Write a function that takes a string of parentheses, and determines if the order of the parentheses is valid. The function should return true if… Read More »Valid Parentheses in Java

The challenge Write a function that determines whether a string is a valid guess in a Boggle board, as per the rules of Boggle. A… Read More »Boggle Word Checker in Java

The challenge Write a function that reverses the bits in an integer. For example, the number 417 is 110100001 in binary. Reversing the binary is 100001011 which is 267. You can assume… Read More »Reverse the bits in an integer in Java

The challenge Write a function that accepts two square matrices (N x N two dimensional arrays), and return the sum of the two. Both matrices being… Read More »Matrix Addition in Java

The challenge The number 81 has a special property, a certain power of the sum of its digits is equal to 81 (nine squared). Eighty… Read More »Numbers that are a power of their sum of digits in Java

The challenge You have to give the number of different integer triangles with one angle of 120 degrees which perimeters are under or equal a… Read More »Integer triangles in Java

The challenge You’re given a square consisting of random numbers, like so: Your job is to calculate the minimum total cost when moving from the… Read More »Minimum path in squares in Java

The challenge Create a function that returns an array containing the first l digits from the nth diagonal of Pascal’s triangle. n = 0 should generate the first diagonal of… Read More »Pascal’s Diagonals in Java

The challenge Given an unsorted array of integer values, find the maximum positive sum of any contiguous range within the array. An array containing only… Read More »Maximum Contiguous Sum in Java

The challenge You’re going to provide a needy programmer a utility method that generates an infinite sized, sequential IntStream which contains all the numbers in a… Read More »Fibonacci Streaming in Java

The challenge In this challenge you must convert integers numbers from and to a negative-base binary system. Negative-base systems can accommodate all the same numbers… Read More »Base-2 in Java

The challenge Consider the following series: 0,1,2,3,4,5,6,7,8,9,10,22,11,20,13,24…There is nothing special between numbers 0 and 10. Let’s start with the number 10 and derive the sequence. 10 has digits 1 and 0. The next possible number… Read More »Unique digits sequence in Java

The challenge The palindromic number 595 is interesting because it can be written as the sum of consecutive squares: 6^2 + 7^2 + 8^2 + 9^2 + 10^2… Read More »Palindrome integer composition in Java

The challenge Implement a function that receives two IPv4 addresses, and returns the number of addresses between them (including the first one, excluding the last… Read More »Count IP Addresses in Java

The challenge Given two different positions on a chess board, find the least number of moves it would take a knight to get from one… Read More »Shortest Knight Path in Java