I have a problem with a sentence that says
" I haven't read today's newspaper yet. I (didn't-don't) have time."
Which answer is the correct answer ?
It all depends on the circumstances.
Suppose it is evening, and you are sitting down to read the newspaper that was delivered earlier today. You could say "I haven't read today's newspaper yet. I didn't have time." So you didn't have the time earlier, but
now you do have the time to do it.
Suppose you are half way through a very busy day. Someone asks you what you think of an article in today's paper. You could say "I haven't read today's newspaper yet. I don't have time." So you didn't have the time earlier, and you
still don't have the time to do it now.