Adding questions in topic wise order

[MillennialPirate]

I would like to contribute and add the feature of topic wise problems from LeetCode and GeeksForGeeks so that beginners in DSA can find the patterns among the questions and find it easy to solve the problems. Along with this, I would like to give an additional feature of edge test cases which will help to learn more about debugging the code and the corner cases where it fails.
Regards,
Siddharth.S.Chandran