If you enter into the world of data structure and you are in the 2 semester of graduation, then firstly you buy “Data Structure by Seymour Lipschutz“.
It has a simple grammar and simple algorithm and will give you the briefing of the concept in simple terms. But if you read this you will only get 60% to 70% in the examination. This is not for GATE.
Second book is Data Structures through C language by Samiran Chattopadhyay. This is a very good book. Also, if you read this book thoroughly then interviewer will be impressed by you. 
This book is sufficient for GATE and NET.
You can also buy Data Structures And Algorithms Made Easy and its author is Narasimha Karumanchi.
You can also buy Fundamentals of Data Structures in C by Sahni & Horowitz. This is the another best book for data structure.
