Explanation for the mathematical solution of atcoder problem E — Σ[k=0..10^100]floor(X／10^k)
Difference between en2 and en3, changed 97 character(s)
Hello codeforces, I solved [This problem](https://atcoder.jp/contests/abc233/tasks/abc233_e) from atcoder with the "Obvious" **brute-force** solution which is O(N). But when I take a look at the editorial I found a **Beautiful** [mathematical solution](https://atcoder.jp/contests/abc233/editorial/3194) that solves it in O(1)<strike>O(1)</strike> O(N) but with a lower constant factor, use lower memory and easy beautiful code. ↵
But unfortunately, I didn't understand it so Can anyone please explain it to me? ↵
↵
I really appreciate any help you can provide.

History

 
 
 
 
Revisions
 
 
  Rev. Lang. By When Δ Comment
en3 English Omar_Hafez 2022-05-28 12:35:44 97 Tiny change: 'ves it in O(1). \nBut un' -> 'ves it in <strike>TO(1)</strike>T. \nBut un'
en2 English Omar_Hafez 2022-05-27 21:49:07 5
en1 English Omar_Hafez 2022-05-27 21:48:12 553 Initial revision (published)