Hi , I am a Java developer with 3.5 years of development experience. I want to apply for product bases companies like Amazon , Google , SAP etc.

I have never prepared DS/Algo extensively before. How do I prepare myself for the coding interviews ?

What topics should I focus on , how many questions should I solve ? What type of questions(difficulty level) should I practice , considering I have 3 months to prepare ? What should be my strategy?

Your inputs are be highly appreciated

Thanks !!