Does it? Both are implementations and explanations of a well-known algorithm. Most articles on quicksort will also look alike, but there's no reason to assume the author has plagiarized anything.
So? Wikipedia is one of the most convenient, large English corpora available, and I doubt there are many significantly different ways to write the bit of functionality that's built up here. I'm not sure if that's what you're meaning to suggest, or that there was some kind of plagiarism / inspiration going on here.
I saw a case once, I forget where, when someone was accused of plagiarising from wikipedia and the truth was that they'd themselves written a large part of the wikipedia article.
True, but it’s also common for people to acknowledge where their DNA came from.
You would likely be called out if you tried to hide that fact in order to seem more accomplished than your are. If for instance your dad is the owner of the company you are working at, you’d be rightfully be called out if you tried to hide the fact that your accomplishment is lessened by the fact that you copied your fathers DNA.
No one is claiming the author did anything wrong in copying the source material for his article. However it is wrong to not provide proper attribution, especially when it’s as easy as an “inspired by link” at the bottom.