Is it hard to get into a get into a good University of you didn't have good grades in 9th and 10th grade?

Hi, I'm going to the 11th grade. I only have two years left in school and I didn't do that well in my freshman & sophomore year in high school at all. I just got by just to be honest. I don't want that on my college resume. I want to have excellent ACT/SAT scores and have great grades for my upcoming junior & senior year of high school. I know that colleges look at your high school grades starting freshman year, but I'm not giving up. So my question is, if I get great grades,work really hard,get involved in some sort of an extra curricular activity,score well in on my ACT/SAT test(s), and rank top of my class, do you think I have a shot of getting into a good college such as USC, Berkley, or maybe even Vanderbilt University? I know that they are competitive colleges, but I want a full ride scholarship. Help please!! What should I do???