According to me,
Physics would be the most difficult. You have to devote most of your time learning DS and algorithms along with mathematics which will be tougher than 10+2, especially ODE and LA.
It is going to be a long first year.
Around half of the students in my batch didn’t opt for Computer Science in their 11th and 12th class.
They turned out fine after a year, with initial struggle, as we have algorithm and data structures subject in the first semester itself.
So you can cope up with the course, by putting more hours of hard work to understand the basics.