Ask HN: I just wrote an O(N) diffing algorithm – what am I missing? 7 by keithwhor | 5 comments on Hacker News. Hey folks, I've been building a rendering engine for a code editor the past couple of days. Rendering huge chunks of highlighted syntax can get laggy. It's not worth switching to React at this stage, so I wanted to just write a quick diff algorithm that would selectively update only changed lines. I found this article: https://ift.tt/2lIuVkG With a link to this paper, the initial Git diff implementation: https://ift.tt/1GF9uI8 I couldn't find the PDF to start with, but read "edit graph" and immediately thought — why don't I just use a hashtable to store lines from LEFT_TEXT and references to where they are, then iterate over RIGHT_TEXT and return matches one by one, also making sure that I keep track of the last match to prevent jumbling? The algorithm I produced is only a few lines and seems accurate. It's O(N) time complexity, whereas the pa