what to learn and what to do and (what not to do )to get into product based companies
First of all, LVM Reddy, it is ver very important to consider which college you are pursuing your degree from. If it is an IIT, IIIT or a NIT, rest assured as product based companies like Amazon, Flipkart will be surely visiting your campus for recruitment.
All you need to would be maintain a good CGPA/ GATE score ( and by good I mean above 85%) and be really good at your core subjects ( which is automatically assumed as you are scoring above 85% in GATE)
But if you are not from the above mentioned colleges, you need to at work really hard to be considered by these companies when you directly apply for their job:
1. 85% in GATE score + Your CGPAs
2. Great analytical skills and efficent in using programming to solve any given problem
3.Be eloquent in C, especially in subjects like Data Structures, Array, Pointers, Functions. Writing algorithms should must be a cakewalk for you. ( Refering to C Programming by Dr.Dennis Ritchie can be excellent)
4. Learn Linux. It can become your plus point
5. Contribute to any open-source project like LANCE, HADOOP or LINUX itself.
6. And most importantly, land an internship at: IITs, IIITs, NITs, product-based companies,etc.
good luck!