The Array Height Checker Problem in Java
The challenge
Students are asked to stand in non-decreasing order of heights for an annual photo.
Return the minimum number of students that must move …
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In-depth guides, insights, and best practices for modern software engineering
Find the Squares of a Sorted Array in Java
The challenge
Given an array of integers A sorted in non-decreasing order, return an array of the squares of each number, also in sorted …
Sorting a Java Array by Parity
The challenge
Given an array A of non-negative integers, return an array consisting of all the even elements of A, followed by all the odd elements of …
Remove Duplicates from Sorted Array in Java
Say you have an array of primitive integers and you want to remove all duplicates.
You can find out how many non-duplicate integers are in the array …
Read Article →Replace Elements with Greatest Element on Right Side using Java
The challenge
Given an array arr, replace every element in that array with the greatest element among the elements to its right, and replace the last …
The Valid Mountain Array Problem using Java
Introducing the problem
Given an array A of integers, return true if and only if it is a valid mountain array.
Recall that A is a mountain array if …
Read Article →HashMaps (aka: Dictionaries) in Python
Introduction
Java has a built-in called HashMap. It allows you to store and very quickly retrieve key value pairs.
In Python, this is called a …
Read Article →Find Numbers with Even Number of Digits using Java
The challenge
Given an array nums of integers, return how many of them contain an even number of digits.
Example 1:
Input: nums = [12,345,2,6,7896] …Read Article →
The Relational Database Model
Relational databases first made an appearance in the mid-1970s, between the years 1974 and 1977 with the creation of Ingres and System R which led to …
Read Article →How to use a Java HashSet by example
What is a HashSet
A HashSet is an unordered collection containing unique elements. It has the standard collection operations Add, Remove, Contains, …
Get The Shortest Path in Binary Matrix using Python
The challenge
In an N by N square grid, each cell is either empty (0) or blocked (1).
A clear path from top-left to bottom-right has length k if and …
Palindrome Partitioning in Python
The problem
Given a string s, partition s such that every substring of the partition is a palindrome.
Return all possible palindrome partitioning of s …
Read Article →Faster alternative to MySQL Delete Table Contents / Truncate
From time to time you might have some rather big tables that you want to delete all the data quickly and start afresh.
You have a few options at this …
Read Article →Best Time to Buy and Sell Stock with Python
The problem
Say you have an array prices for which the ith element is the price of a given stock on day i.
Design an algorithm to find the maximum …
Read Article →IPv4 CIDR Chart
CIDR stands for Classless Inter-Domain Routing and is a method for allocating IP addresses as well as for IP routing.
It was introduced in 1993 by the …
Read Article →Recursively Delete Files and Folders and all Contents using PHP
Below is a quick and easy way to recursively delete all files and folders in a given path using PHP.
function destroy_dir($dir) {
if (!is_dir($dir) …Product Update: ADD becomes Serengeti
As a product update; The “Autonomous Distributed Database”, otherwise known as simply ADD has been renamed to Serengeti.
The Serengeti is …
Read Article →SQL to Append all Fields if Shorter than a set Length
This came in very handy for me at one point because I needed to have a certain field in each row 14 characters long, but half of them were only 12 …
Read Article →Validate Email Address in Javascript
Need a quick client-side email validation? Below is a simple JavaScript regular expression to validate email addresses. …
Read Article →Remove hash from window.location in Javascript
E.g. URL:<br>http://example.com/?option=1&task=2&listing_id=36&layout=4&table=5#some_hash_value_here
So how would you get the …
Read Article →The Benefits and Dangers of Artificial Intelligence
Artificial Intelligence (AI) is usually defined as the science of making computers do things that require intelligence when done by humans. (Jack …
Read Article →The Decoded String at Index using Java
The Challenge
An encoded string S is given. To find and write the decoded string to a tape, the encoded string is read one character at a time and …
Timing Issues in Real-time systems
What are Real-time Systems?
If you look up the term “real-time” in a dictionary, it will tell you that it is the actual time during which …
Read Article →Find the Minimum Absolute Difference in BST using Java
The question
Given a binary search tree with non-negative values, find the minimum absolute difference between values of any two nodes.
Example: …
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