Feature iterative flood fill #6584
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- nested class Point: helper class, represents point in 2D field (x,y) - shouldSkipPixel method: helper method to validate point - floodFill method: iterative version of floodFill, uses Queue to add and poll Points and change it color if allowed
-same tests as for normal floodFill and test for a big image
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## master #6584 +/- ##
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+ Coverage 76.45% 76.48% +0.02%
- Complexity 5985 6001 +16
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Files 716 717 +1
Lines 20265 20290 +25
Branches 3929 3933 +4
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+ Hits 15494 15518 +24
- Misses 4180 4181 +1
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CrodiYa
requested review from
DenizAltunkapan,
alxkm and
yanglbme
as code owners
- Move private methods after public methods for better readability - Add class-level JavaDoc documentation with algorithm description and links to references
DenizAltunkapan
approved these changes
Oct 9, 2025
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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
Pointto 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
dxanddy. 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