Sharkretriver wrote:For competitions, a file with a list of 5 scrambles is prepared. The first solve for any person uses the first scramble, for the second solve, the second scramble, etc.
Scrambles are 19 to 21 moves long, I think, and are computer generated. The cubes are scrambled with white/black on U and green on F by hand (volunteers, not competitors).
Adding to that, the rules for scrambling can be seen here
on the World Cube Association's website. Also, the program that is used for generating scrambles is here
Sharkretriver - Sometimes competitors do scramble the puzzles (probably only in rare cases). For example, at one point during the 2013 World Championship, competitors (or anyone) who could scramble a megaminx quickly were invited to do so (for the megaminx event). They probably wouldn't have allowed competitors of that round to help though.