Question

Did you think you - me somewhere before?

Answer 1

Hi bro
Here's the correct answer:

Did you think you had seen me somewhere before?

Here we should use 'Had seen' because the person is asking another whether he/she has met him/her before. So it should be in past tense.

Hope dis helps

Answer 2

This is the correct answer :

Did you think you had seen me somewhere before?

Did you think you______ me somewhere before.
The answer is saw.