What is your main purpose of practicing ?

I've been submitting for "ICPC 2025 Online Winter Challenge powered by Huawei" and suddenly I saw this message :

MikeMirzayanov are you kidding me ?

I have several questions in mind, like:

1. Is +, -, *, / Actually O(1)? It’s commonly said that these operations are O(1), but is that always true?

2. Is x % y Slower Than x-(x / y) * y? I’ve heard people say "modulo is slow", so why not just avoid % and use x-(x / y) * y instead?

I hope you understand my curiosity!

Hi MikeMirzayanov,

I wanted to suggest adding a way for users to report suspicious activity during contests, like AI-generated code or other cheating methods. Right now, some people break the rules, making competitions unfair.

A reporting system could let users report suspicious submissions. If an account gets multiple reports, moderators could investigate (checking user profile, reviewing code, etc.) and take action if cheating is confirmed.

This could help keep contests fair and discourage cheating. What do you think?

Thanks for your efforts!!

Today I faced a problem in "Codeforces Round 794 (Div. 1)" which I didn't solve yet, but felt that I've solved it before , after a little searching I found that it's existed before in "Educational Codeforces Round 174 (Rated for Div. 2)" with a 99.9% similarity in the solution !!!!

Here is the older version : https://mirror.codeforces.com/problemset/problem/1685/B

Solution 1: https://mirror.codeforces.com/contest/1685/submission/311499198

The newer one : https://mirror.codeforces.com/contest/2069/problem/E

Solution 2: https://mirror.codeforces.com/contest/2069/submission/311500284

Does anyone facing an issue with the standings page ?

Hi Codeforces. I've submitted an Accepted solution on 22/2/2025 for an already solved problem (resolved it) but it didn't appear on my activity board as a green square and my (in a row days) has been ruined :|

Is this a bug?? if so please fix it.

Hi Codeforces :) Recently I've reached CM and am looking for to reach Master. So I want some advice from you if you have reached Master or more, like what topics should I focus on, websites to practise on and some references that may help.

Thank you anyway..