Add solutions for GeeksforGeeks practice problems

[jitendrajat10099]

[RisingGeek]

I would like to add solutions for stack problems.

[jitendrajat10099]

You can contribute it .
Just make another folder
GeeksforGeeks/Stack/problem
and provide link in comment as specified in Readme

[vrakr19]

Added one basic stack problem solution from gfg.

[RisingGeek]

Added one basic stack problem solution from gfg.

where?

[RisingGeek]

PR for "Two stacks in an array" - #24

[RisingGeek]

Stack using two queues - #39

[rishika1802]

I will like to to add linked list solutions of geeks for geeks practice problems