Top colleges offering a btech course in Computer Science branch are mentioned below:

• Indian Institute of Technology, Delhi
• Indian Institute of Technology, Bombay
• Indian Institute of Technology, Kharagpur
• Indian Institute of Technology, Kanpur
• Indian Institute of Technology, Madras
• Indian Institute of Technology, Roorkee
• Manipal Institute of Technology, Manipal
• Delhi Technological University, Delhi
• Birla Institute of Technology and Science, Pilani
• Jadavpur University, Kolkata
• Indian Institute of Technology, BHU
• National Institute of Technology, Tiruchirappalli

The admission process can vary a bit but mostly the intake is through Jee main entrance exam.

Good Luck.