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 …
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In-depth guides, insights, and best practices for modern software engineering
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 …
Calculate the Surface Area and Volume of a Box with Java
The challenge
Write a function that returns the total surface area and volume of a box as an array: [area, volume]
The solution in Java
We know that …
Read Article →Find Numbers which are Divisible by given Number in Java
The challenge
Complete the function which takes two arguments and returns all numbers which are divisible by the given divisor. First argument is an …
Read Article →How to Split a Subdirectory to a New Git Repository and Keep the History
There comes a time when you need to split out a subdirectory into it’s own git repo.
This is a very simple task if you don’t care about …
Read Article →Get the Maximum XOR of Two Numbers in an Array in Java
The challenge
Given a non-empty array of numbers, a, a1, a2, … , an-1, where 0 ≤ ai < 231.
Find the maximum result of ai XOR aj, where 0 ≤ i, j …
Read Article →How to Get the Opposite of a Number in Java
The challenge
Given a number, find its opposite.
Examples:
1: -1
14: -14
-34: 34
The solution in Java
We return the number itself multiplied by a …
Read Article →How to Find the Area or Perimeter of a 4-sided Polygon using Java
The challenge
You are given the length and width of a 4-sided polygon. The polygon can either be a rectangle or a square.
If it is a square, return …
How to Parse Int from Char in Java
The challenge
We take in a String where the first place contains a number, write a function that takes in this String and returns an int containing …
How to Search a Binary Tree in Java
The challenge
Given a sorted (in ascending order) integer array nums of n elements and a target value, write a function to search target in nums. If …
How to Rotate a Singly Linked List in Java
The challenge
Given a linked list, rotate the list to the right by k places, where k is non-negative.
Example 1:
Input: 1->2->3->4->5->NULL, k = 2 …Read Article →
How to Insert into a Binary Search Tree using Java
The challenge
You are given the root node of a binary search tree (BST) and a value to insert into the tree. Return the root node of the BST after the …
Find the Complement of Base 10 Integer in Java
The challenge
Every non-negative integer N has a binary representation. For example, 5 can be represented as "101" in binary, 11 as …
Solve the Number of Recent Calls Challenge in Java
The challenge
You have a RecentCounter class which counts the number of recent requests within a certain time frame.
Implement the RecentCounter …
How to Calculate the Summation of a Number in Java
The challenge
Write a program that finds the summation of every number from 1 to num. The number will always be a positive integer greater than 0.
For …
Read Article →How to Calculate all Unique Combinations of a Target using Backtracking in Java
The challenge
Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where …
Who is going to pay for the wall? in Python
The challenge
Don Drumphet lives in a nice neighborhood, but one of his neighbors has started to let his house go. Don Drumphet wants to build a wall …
Read Article →Calculate the Total Amount of Points using Java
The challenge
Our football team finished the championship. The result of each match look like “x:y”. Results of all matches are recorded …
Read Article →Calculate the biggest of 3 numbers using Java
The challenge
Task
- Given three integers
a,b,c, return the largest number obtained after inserting the following operators and brackets:+,*,() - In …