Finding a Needle in a Haystack in Java
The challenge
Can you find the needle in the haystack?
Write a function findNeedle() that takes an array full of junk but containing one …
Java
342 articles about java development, tools, and best practices
How to Solve the Champagne Tower in Java
The challenge
We stack glasses in a pyramid, where the first row has 1 glass, the second row has 2 glasses, and so on until the 100th row. Each glass …
How to Solve the 132 Pattern in Java
The challenge
Given an array of n integers nums, a 132 pattern is a subsequence of three integers nums[i], nums[j] and nums[k] such that i < j < …
How to Replace all Vowels in a String in Java
The challenge
Replace all vowel to exclamation mark in the sentence. aeiouAEIOU is vowel.
Examples
replace("Hi!") === "H!!" …How to Get the N-th Power in Java
The challenge
You are given an array with positive numbers and a number N. You should find the N-th power of the element in the array with the index …
Read Article →How to Count the Minimum Depth of a Binary Tree in Java
The challenge
Given a binary tree, find its minimum depth.
The minimum depth is the number of nodes along the shortest path from the root node down to …
Read Article →How to Solve the House Robber II Challenge in Java
The challenge
You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed. All houses at …
Read Article →How to Clone a Graph in Java
The challenge
Given a reference of a node in a connected undirected graph.
Return a deep copy (clone) of the graph. Effectively a graph copy.
Each …
Read Article →How to Return Random Values in Java
The challenge
Ghost objects are instantiated without any arguments.
Ghost objects are given a random color attribute of white" or …
Read Article →How to Compare Version Numbers in Java
The challenge
Compare two version numbers version1 and version2.
If <em>version1</em> > <em>version2</em> …
How to Return the First N Elements in Java
The challenge
Create a method take that accepts a list/array and a number n, and returns a list/array array of the first n elements from the …
Read Article →How to Search a 2d Matrix/Array in Java
The challenge
Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:
- Integers in each …