add Flood Fill Algorithm

[KhaledElshamy]

Checklist

• [x] I've looked at the contribution guidelines.
• [x] This pull request is complete and ready for review.

Description

add Flood Fill Algorithm using Swift language

[richard-ash]

@KhaledElshamy thanks for the submission! Flood Fill looks like a fun algorithm to add to the repo.

The code is good, however I think the readme could use another pass. Could you update it to provide more context/description around the problem the algorithm solves?

A good algorithm in the repo to model the readme off of is Linked List

Let me know if you have any questions!

[KhaledElshamy]

Thanks Richard, Yes I'll update the readme to provide more description around the problem the algorithm solves.

[KhaledElshamy]

@richard-ash I've updated the README.

[KhaledElshamy]

@richard-ash Is there any problem in the algorithm to be accepted?