Unable to understand the editorial

Revision en2, by skpro19, 2017-08-22 14:13:09

The question is this-> 757C

I am unable to understand anything in the editorial, as well as the given code. Can someone please help?


  Rev. Lang. By When Δ Comment
en2 English skpro19 2017-08-22 14:13:09 1961
en1 English skpro19 2017-08-22 13:49:32 2188 Initial revision (published)