Feature iterative flood fill #6584
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BFS Flood Fill algorithm
Project already has Flood Fill
This project already has a Flood Fill algorithm, but it is DFS.
For any big "image" DFS version won`t work because of stack overflow.
The BFS version, on the other hand, handles large "images" without any problems.
My first "big" project on Java was simple pixel paint app and that was my first time encountering StackOverflowException and I was very confused: it took me some time to figure out the problem and solution.
So, it would be useful to have this example of this algorithm here.
A similar version of this algorithm can be found here: https://www.geeksforgeeks.org/dsa/flood-fill-algorithm/
Main difference - this version looks for diagonals too
Technical details
This version uses queue and helper class
Point
to traverse.While queue is not empty, the "pixel" is painted and "pixels" around it are added to queue (if coordinates are in boundaries and colour is not the same).
Directions for new "pixels" stored in arrays
dx
anddy
. First four - horizontal and vertical, second four - diagonals.It is achievable to store coordinates (x, y) in long, using bit mask, but it`s too much and possibly can lead to collision.
Tests were copied from original FloodFill and one test was added to demonstrate that BFS handles "big images".
To be honest, I am not entirely sure in what package to add this, so "others" was picked.
clang-format -i --style=file path/to/your/file.java