Project Ideas for B.TECH (CS)

What exactly are you looking for ideas based only on data-structures.

I think of them as a pair which will get the optimum solution,
an algorithm will run faster with most compatible data-structure and a data-structure is required if and only if it makes any algorithm faster or consumes less memory, I shall leave it up to you to find the examples of the above category.

Classic idea would be sorting-searching algorithms.
There are numerous algorithms which lie in sorting-searching domain.
Try implement them, study them who knows, you might develop your own some day, making all of us proud.

You can go for board game programming as it might help you to choose various data-structures and algorithm, lets say we go for game of finding some shortest path,
You can try this with various approaches, like starting with plain BFS then going for Dijkstra's,Bellman-Ford,A* with memoization, without memoization.

Now let us take example of say tic-tac-toe,It is said that a tic-tac-toe game is a draw if played perfectly. But can you re-verify? This can be easily be solved using multiple if-else blocks but then we are looking for algorithm, can you come up with something? There are plenty of them online, you can read about them and refer their pseudo-code, write your code, compare. Can you show how many games can first player win when second player does not play optimum? Ask such question to yourself, and if you don't know the answer then program it and find it out, post it here and CEans would be glad in verifying if they have time, or if you are stuck then we shall help you.
You can also go for developing chess, but I shall suggest you start with tic-tac-toe.

If you are interested in mathematics, then try to dive into number theory best example would be primes can you find all primes from 1 to 10000000? How long does your algorithm take? Can you do it any better?.

Saying this, you should learn a programming language first, and by that I don't mean knowing only syntax.

You can also go further for image processing algorithms, which I leave for you to google up and come back.