There are 100 pictures and 100 html files. In one html file there should be a link to 1 picture, i.e. 1.html contains a link to 2.png, 2.html contains a link to 2.png, and so on. Sit rewriting with your hands is not an option, maybe you can somehow do it more conveniently?
In Notepad ++ and Atom I did not find such functionality.