Lots of geeky customers visit our chef’s restaurant everyday. So, when asked to fill the feedback form, these customers represent the feedback using a binary string (i.e a string that contains only characters ‘0’ and ‘1’. Now since chef is not that great in deciphering binary strings, he has decided the following criteria to classify […]
The problem: In England the currency is made up of pound, £, and pence, p, and there are eight coins in general circulation: 1p, 2p, 5p, 10p, 20p, 50p, £1 (100p) and £2 (200p). It is possible to make £2 in the following way: 1×£1 + 1×50p + 2×20p + 1×5p + 1×2p + 3×1p […]
Say you have a URL that redirects to another (e.g., bit.ly). How do you find the real URL behind the redirect? You can do this in Java using the HttpURLConnection class. Like this: String url = "http://bit.ly/23414"; HttpURLConnection con = (HttpURLConnection) new URL(url).openConnection(); con.setInstanceFollowRedirects(false); con.connect(); String realURL = con.getHeaderField(3).toString(); You basically create a connection, disable […]
If you use an IDE like Eclipse to develop your Java programs then using external libraries is pretty straight forward. You just need to add the JAR file to your project and then right click on it and add it to the build path, and the IDE will do the rest of the work for […]
As a Linux user you’ll inevitable need to search around for a specific file once in a while, be it a configuration file you need to edit or a version of a document you somehow lost. There are three basic ways to search for files using the command line: 1. locate The locate command is […]
As far as I know there are 10 types of programmers around: emacs programmers and vi programmers. Jokes aside I think both text editors are fine, but I prefer vi/vim. The problem is that getting started with it is not trivial, as once you open it you’ll be presented with a blank screen and a […]
Below you’ll find some useful Linux tools and commands you can use to manipulate and process text. 1. less In my opinion the best tool for visualizing text files. It allows you to easily scroll back and forward (using both lines and pages), and it also comes with search and other functions. Use: less file.txt […]
The problem: Surprisingly there are only three numbers that can be written as the sum of fourth powers of their digits: 1634 = 14 + 64 + 34 + 44 8208 = 84 + 24 + 04 + 84 9474 = 94 + 44 + 74 + 44 As 1 = 14 is not a […]
Below you’ll find the basic Regex patterns you can use to match, edit and replace strings. I am using the Java/Perl Regex flavor, so the patterns might be slightly different if you are using another programming language or platform. Java Implementation Here’s a simple Java sample that uses the Regex library. It will try to […]
The problem: Consider all integer combinations of ab for 2 ≤ a ≤ 5 and 2 ≤ b ≤ 5: 22=4, 23=8, 24=16, 25=32 32=9, 33=27, 34=81, 35=243 42=16, 43=64, 44=256, 45=1024 52=25, 53=125, 54=625, 55=3125 If they are then placed in numerical order, with any repeats removed, we get the following sequence of 15 […]