Tree Array (2D/1B) Explanation | Codeforces Round 728

Описание: Problem: https://codeforces.com/contest/1541/p...
Implementation: https://codeforces.com/contest/1540/s...

Expected Value Tutorial:
https://codeforces.com/blog/entry/62690
Modular Inverses Tutorial (for expressing fractions under mod):
https://cp-algorithms.com/algebra/mod...

I mainly do Codeforces and AtCoder, with the occasional CodeChef contest
CF: https://codeforces.com/profile/hu_tao
AtCoder: https://atcoder.jp/users/MagentaCobra
CodeChef: https://www.codechef.com/users/magent...

Stats as of 6/25/2021:
AtCoder: 1987 (max 2045)
Codeforces: 2223 (max 2223)
Codechef: 2254 (max 2254)