Of course you can use the algorithm. I believe in sharing freely (especially when it probably wasn’t my idea to start with 
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@Ignatz I finally worked an example on graph paper (about 10 pixels) and there were times when 3 of the 4 pixels were already visited. So I could see where the increase in speed would result by checking for visited pixels. I didn’t think that much about the speed of my code, I was more interested in watching it do the fill. That’s what’s so great about this forum, someone will always find a better way of doing things. That’s the whole purpose, to see how someone else would code it. @Luatee I think anything posted on the forum is for anyone’s use unless it’s specified not to be.