Anxious for QA interview after 5yrs

I am looking for changing company after 5 yrs, target was big companies like Amazon, MS, Salesforce , gave few interview in small companies recently but failed in that badly. I am anxious right now. I have brushed up with basic array and string programs and framework creation of UI(selenium) + backend(restassured). Is there anyone who can guide me what topics I should prepare for the lead QA SDET interview.

1. How many string and array related problem should I do and what should be difficulty level?
2. Is there any other data structure should I prepare?
3. What practice website should I prepare for Programming questions?