After looking at the hints for 1925B (https://codeforces.net/problemset/problem/1925/B), I realized the solution by knowing the properties of gcd(a,b) = gcd(a, a + b). But since this is codeforces, I'm wondering how I would have got to the solution if I hadn't known this property about gcd. For those who have solved this without using mathematical properties, how did you solve this?

Which one is more reliable? There are 1000s that I cannot solve, and 1500s and even 2000s I can easily solve. I used to think that ratings was the measure of skill, but recently it seems that looking at the number of correct submissions for problems is proving a better measure for me. Am I mistaken that a 1000 rated person should be able to solve all 1000s? I am now ranking myself based on submission number now, and it has proven far more useful in searching for problems my level. What do you guys think?

What is the difference between the prewritten sqrt function that I used here : https://codeforces.net/contest/1737/submission/222667221 and my own written sqrt function that I wrote here : https://codeforces.net/contest/1737/submission/222667916?

I understand stuff about precision and things like that, but I'm just rounding down, so even if something is like 2.0000067 it should still yield the correct answer. Please explain! I feel like this just happens over and over again: everytime I use sqrt(x) it always fails to get AC and I have to write my own sqrt function, even if my algo is correct.

Anybody know why this happens? I'm completely thrown off on how to debug this, since the bug disappears when I do cout. (this is only on my local machine, but I will provide the code)

My submission : https://codeforces.net/contest/1851/submission/221618285

Please provide some tips, because google is not.

Before, I used to spend hours a day thinking about a single problem before giving up, but now I've decided to improve efficiency by limiting myself to 30-40 minutes per problem. Is this too short? How long do you guys spend on problems before giving up-if you give up at all?

For this problem : https://codeforces.net/contest/1805/problem/C, I submitted this solution: https://codeforces.net/contest/1805/submission/215278227.

The runtime is 78 ms.

I then submitted the exact same solution with a simple comment at the top : https://codeforces.net/contest/1805/submission/215278404.

The runtime is 93 ms.

Although meaningless here, what accounts for the difference in runtime? I would understand if the difference was 1 or 2 ms off, but 15 ms off seems like a lot for two exact same solutions.

Just curious, do problem setters create some test cases by hand and then randomly generate the rest or are all the test cases just randomly generated within the bounds of the problem?

Remebering my beginner days, I used to have a very hard time even solving 800s. I propose that div 4 starts with problems with ratings like 500 or even 400, so that even beginners have a chance of solving codeforce problems. Not only would this get more people into cp, it would also grow the codeforce community.

I really like the new way they write tutorials, where they offer small hints you can completely read through before the acutal tutorial, but there are very few editorials like this and most of them are recent. When I do old problems and I get stuck, I'm always afraid to read the tutorial since I might end up finding out a major hint when all I wanted was a small hint. What do you guys do when you are stuck? Do you just read all of the tutorial? Small parts of it? I want to have a small push in the right direction, but still figure out 70% of the solution myself, while reading tutorials might give me 50% of the solution.

Hi, in my solution below, I created a algorithm that uses only addition, subtraction, and some simple functions to get my answer. https://codeforces.net/contest/1811/submission/202086856 However, this O(1) solution times out to this problem : https://codeforces.net/contest/1811/problem/B

Can I have an in depth explanation as to why this is the case? I suspect it is because I'm using doubles, but even then I don't see how this can cause such it to be so slow.