"Being beaten to it by a week"? [closed]
I think you've heard right, although the indefinite article is important, and it appears to be missing in your question title ("by week" vs "by a week").
In this case "it" is the solution of the problem, and someone has beaten you to that solution, i.e. solved the problem first, and the amount of time they've beaten you by is "a week", which just means that you were a week away from solving it when they found the solution.