Spring Boot no main manifest attribute, in
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Java
345 articles about java development, tools, and best practices
Matrix Addition 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 …
Numbers that are a power of their sum of digits 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 one (81), is the …
Read Article →Integer triangles 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 certain …
Read Article →Minimum path in squares in Java
The challenge
You’re given a square consisting of random numbers, like so:
var square = [
[1,2,3],
[4,8,2],
[1,5,3]
];
Your job is …
Read Article →Pascal’s Diagonals 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 …
Maximum Contiguous Sum 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 …
Read Article →Fibonacci Streaming in Java
The challenge
You’re going to provide a needy programmer a utility method that generates an infinite sized, sequential IntStream which contains …
Base-2 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 …
Read Article →Unique digits sequence 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 `` and 10.
Let’s …
Read Article →Palindrome integer composition 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 + …
Count IP Addresses in Java
The challenge
Implement a function that receives two IPv4 addresses, and returns the number of addresses between them (including the first one, …
Read Article →Shortest Knight Path 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 to the other. The …
Read Article →All Balanced Parentheses in Java
The challenge
Write a function that makes a list of strings representing all of the ways you can balance n pairs of parentheses
Examples …
Read Article →Human readable duration format in Java
The challenge
Your task in order to complete this challenge is to write a function which formats a duration, given as a number of seconds, in a …
Read Article →Simple string expansion in Java
The challenge
Consider the following expansion:
// because "ab" repeats 3 times
solve("3(ab)") == "ababab"
// because …Hamming Numbers in Java
The challenge
A Hamming number is a positive integer of the form 2i3j5k, for some non-negative integers i, j, and k.
Write a function that computes …
Read Article →Block sequence in Java
The challenge
Consider the following array:
[1, 12, 123, 1234, 12345, 123456, 1234567, 12345678, 123456789, 12345678910, 1234567891011...]
If we join …
Read Article →Roman Numerals Helper in Java
The challenge
Create a RomanNumerals class that can convert a roman numeral to and from an integer value. It should follow the API demonstrated in the …
Read Article →Closest pair of points in linearithmic time in Java
The challenge
Given a number of points on a plane, your task is to find two points with the smallest distance between them in linearithmic O(n log n) …
Read Article →Find sum of top-left to bottom-right diagonals in Java
The challenge
Given a square matrix (i.e. an array of subarrays), find the sum of values from the first value of the first array, the second value of …
Read Article →Sweeping trees in Java
The challenge
You will be given a list of strings representing nodes in a rooted tree. A visual representation of a very simple rooted tree could be: …
Read Article →Detect Pangram in Java
The challenge
A pangram is a sentence that contains every single letter of the alphabet at least once. For example, the sentence “The quick …
Read Article →Remove the parentheses in Java
The challenge
In this challenge you are given a string for example:
"example(unwanted thing)example"
Your task is to remove everything inside …
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