A left rotation operation on an array shifts each of the array’s elements 1 unit to the left. For example, if 2 left rotations are performed on array [1,2,3,4,5], then the array would become [3,4,5,1,2]. Given an array a of n integers and a number, d, perform d left rotations on the array. Return the…

It’s New Year’s Day and everyone’s in line for the Wonderland rollercoaster ride! There are a number of people queued up, and each person wears a sticker indicating their initial position in the queue. Initial positions increment by 1 from 1 at the front of the line to n at the back. Any person in…

You are given a square grid with some cells open (.) and some blocked (X). Your playing piece can move along any row or column until it reaches the edge of the grid or a blocked cell. Given a grid, a start and an end position, determine the number of moves it will take to…

Lilah has a string, s , of lowercase English letters that she repeated infinitely many times. Given an integer, n, find and print the number of letter a’s in the first n letters of Lilah’s infinite string. For example, if the string s=’abcac’ and n=10, the substring we consider is ‘abcacabcac’ , the first 10…

John works at a clothing store. He has a large pile of socks that he must pair by color for sale. Given an array of integers representing the color of each sock, determine how many pairs of socks with matching colors there are. For example, there are socks n=7 with colors ar=[1,2,1,2,1,3,2] . There is…

Gary is an avid hiker. He tracks his hikes meticulously, paying close attention to small details like topography. During his last hike he took exactly n steps. For every step he took, he noted if it was an U uphill, , or a D downhill, step. Gary’s hikes start and end at sea level and…

Harold is a kidnapper who wrote a ransom note, but now he is worried it will be traced back to him through his handwriting. He found a magazine and wants to know if he can cut out whole words from it and use them to create an untraceable replica of his ransom note. The words…

In this tutorial, a simple but useful data buffering/streaming algorithm is presented. It is not optimal but easy to understand and modify according to your needs… This library assumes that we need to use a big amount of data in a memory limited system. The library handles the all the data transferring procedure in a…

The purpose of this application is just for fun. It started initially by figuring out a way to fake skype that you are in front of your PC but also to randomly create a picture. The application takes control of your mouse and start drawing random pixels in the main area of the window thus…

Messing around with files, i found that i needed some extra functionalities when i Read/Write in a (binary) file. For example i need to read a specific block of bytes with an offset (if exists – not out of bound) as well as write a given block of bytes to a certain address and select…