Hi all , Youtube has taken down my channel for some reason. I have mailed them and asked to about it and asked them to bring it up. Sharing this detail here because many of you are worried about it. Since lectures from youtube are gone , I have removed any post I had on Codeforces where I shared link of lectures. let's see what happens. Don't worry , I have backup of most lectures , even in the worst case if views are gone , lectures will still be there , I will upload them soon. and don't worry , I am still

CodeNCode

Hey CF community. I am going to begin studying independent set in graph (maximal independent set) and edge covering but since my knowledge in discrete mathematics is not very good and I do not know much about these concepts I need to know the following.

1. Prerequisites to Independent set and edge covering (if any)
2. Related articles (would be a bonus)
3. Related problems to practice (would be bonus++)

Thank you for your valuable time.

i am stuck at simple problem , and the problem is that there is no Editorial available for this problem.

The problem is as follows:

Given M (Distinct) integers A1 , A2 , A3 , A4 , A5 ...... , Am , find all integers K , such that remainder of all elements with k is same I.E. A1%K = A2%K = A3%K = ..... = Am%K

and K>1.

Number of elements are 100 , and Ai <= 10^9

My solution is brute force: i am running a loop from 2 to second largest element (which can be upto 10^9) and finding all k , but its giving TLE.

This is the link to the problem

any hint or help would be appreciative. Thanks in advance and happy coding.

I am trying to solve a problem on convex hull(my first problem on convex hull) , but don't know why getting WA. I am using Grahm's scan algo to generate all points of Hull , and then simply calculating the parameter of the hull. please can anyone tell me whats wrong with my code. thank you in advance.

Link to my code

Link to problem

#include<bits/stdc++.h>
using namespace std;

int main()
{
	float x1,x2,y1,y2,x3,y3,x4,y4,ansx,ansy;
	
	while(cin>>x1>>y1)
	{
		cin>>x2>>y2>>x3>>y3>>x4>>y4;
		
		if(x1==x3 && y1==y3)
		{
			ansx = x2-x1+x4;
			ansy = y2-y1+y4;
		}
		
		else
		if(x2==x3 && y2==y3)
		{
			ansx = x1-x2+x4;
			ansy = y1-y2+y4;
		}
		else
		if(x1==x4 && y1==y4)
		{
			ansx = x2-x1+x3;
			ansy = y2-y1+y3;
		}
		
		else
		{
			ansx = x1-x2+x3;
			ansy = y1-y2+y3;
		}
		printf("%.3lf %.3lf\n", ansx, ansy);
	}
}

i dont know whats wrong with code , getting wrong answer. if anyone can point out some problem in the code. thank you in advance. Link to problem