Dear aspirant you have not mentioned anything about your state,exam etc.I assume that it is about JEE-MAINS.So,the rank 45k in general category is very low and you will have very very few or i would say no chance of getting CSE as CSE is preferred by toppers each year.The previous year trends show that you can get a seat in a good state govt. college or the least preferred branches of your home state colleges.So,don't worry you can start your engineering.All the best.

Thanks.