CS majors generally don’t complete IGETC. Focus on technical classes - you will have to complete all major prep listed on assist.org. (it’s generally divided into required and recommended classes I believe - you need all required classes to realistically have a chance, and you’ll want to complete as many recommended classes as possible).
Different schools have different requirements… It’s best to compare the assist pages for UCB/LA/SD and any other UCs you plan to apply to, and complete everything available to you. CS is incredibly competitive, so you will want to keep your GPA high, and complete as many major prep courses listed on assist as you realistically can.
Many CS majors take more than 2 years to complete everything, but from what I understand, it’s doable in two, especially if you take summer classes.