There are multiple rounds to the Facebook Hacker Cup. The Qualification Round lasts 72-hours. Online Round 1 consists of 3 sub-rounds each 3-hours long. Online Round 2 lasts 3-hours long.
Environment
You can use any programming language to solve the problems, using any development environment or text editor, as long as the compiler or interpreter you used for that language is freely available and easy to download and use. Time-limited trials for compilers and interpreters are disallowed. Visual Studio is acceptable as a compiler, since there's a free version of (almost the same) compiler available, Visual Studio Express. Facebook reserves the right to make further exceptions on a case-by-case basis.
The Problems
Each contest consists of 3 algorithmic problems. The problems will be listed in the panel on the top left side of the page. Click on a problem’s name to view the statement for that problem, which will appear in the middle of the page.
The problem statement will be an HTML file, possibly containing images. It will include one or more sample test cases and will have one input file.
Downloading Input
At the bottom of the problem statement will be a link to download the input file. The timer begins immediately after you start to download the input file. You will have six minutes for to upload the output from your program.
You have one chance, to solve the input. You may resubmit during this time. If you run out of time, you cannot download another input file.
Re-downloading Inputs
You may re-download your input file at any time during the six-minute time period.