As I am new to C and algorithm programming, I want to know how should I practice or do coding so that I can write 100 -200 lines of codes as required in the various programming competitions, how much time it will take for one to develop that skills and how to develop smart coding skills.
Well, there are no shortcuts… And this question has been asked over and over again here…
My only advice is that you work and practice very hard, everyday, so that you can keep yourself constantly active and constantly challenging yourself
Motivate yourself by attending competitions and seeing your skills improving with each contest as you always learn something new if you work for it.
When contest ends, dedicate some of your time reading the editorials for the problems carefully, then try to implement the ideas described on them on your favorite programming language and you will improve your implementation skills easily
As for learning algorithms themselves, as they are heavily maths based, I say that working on your mathematical skills is also extremely important, and perhaps the most important thing once you have mastered some data structures and basic algorithms
Best regards and good luck,