“Is it more difficult for an international student to get in than an OOS student?”
I do not know. I know that it is very difficult either way. The problem with applying undeclared is that I do not think that you are guaranteed to be able to get into the computer science program if you do not start there. If applying as undeclared and then switching to computer science was easy than everyone would do it – CS is a very highly desired major at most schools and at UCB.
Computer science is an area where people really do not care much where you went to university. In most cases I do not even know where someone I work with went to university. Occasionally I find out over lunch or a beer.
Where have you gotten accepted?