Heya!!
Since I am from IIT Mandi..I can particularly tell you about that!
Coding culture here is growing at a very fast pace.Seniors here are very humble and you feel free to ask any questions related to coding….moreover there are regularly organised contests on platforms like codeforces and Codechef made by the seniors….this year 11 people from IIT Mandi are selected for gsoc…its the 7 highest in India!!
The programming club regularly organise sessions to get us acclimitized with the coding environment and make us know about the important techniques and algorithms to solve problems.
Hope You choose well keeping in mind these facts!!