UCSD reddit has a PSA, so I thought I would repost here since there are a lot of posts about people getting in undeclared and wanting CS: https://www.reddit.com/r/UCSD/comments/5yrojn/psa_for_incoming_freshmen_who_did_not_get_into_cs/
Edit: Not sure how to link on here, so I’ll post link in comments
It seems as though this website blocks reddit, so I guess you can read about the post there