First leetcode was the coin change problem, but you can use a greedy algorithm to solve it since the denominations include a 1 dollar coin. If you solve it fast they follow up with a very easy tree navigating problem. The second leet code was related to RegEx where they invent a regular expression to match strings, and you build an algorithm that performs the match. Much easier than it sounds, just think it through. The takehome assignment takes between 6-10 hours and involve building an application that displays statistics about your current and historical CPU load. They give you a lot of good hints, so focus on making it pretty and flashy. The "system design" interview is just a UI interview in disguise. They'll describe an application and you just have to come up with what the UI looks like, and ask questions about tradeoffs and what the user's requirements are. Don't dive into system design details, because they will ask you to get back on task with the UI stuff.
