HealthyUG's blog

By HealthyUG, history, 3 weeks ago,

So long story short, Problemset got renamed to Bugabooset. (Full story if you're interested)

Don't get me wrong, I personally find it extremely amazing, but I still want this change to be reverted.

I have some valid reasons:-

• Whenever some newcomer asks me for advice... I say something like, "Go to the Codeforces Problemset and sort the problems by difficulty and then solve a few everyday", now recently what is happening is that, a lot of newcomers can't find the problemset (because it does not exist anymore!!).
• If I tell them to go to the bugabooset, they will ask me what is that and what it means, and that's one story that I do not want to explain to someone for the 348th time!
• The link still points to "http://codeforces.com/problemset", I think this discrepancy is very confusing... Now some might say, we can change it to "http://codeforces.com/bugabooset" but that'll unnecessarily ruin many people's bookmarks (unless old links redirect to the new ones, ok yeah, this one is a moot point tbh)
• Regarding the problem vs question debate: The actual victims are pretty much unaffected by this change. My point is- If they called them "questions" when "problemset" existed, what makes you think they will call them "bugaboos" now? They won't! They'll still call it "question" and many people will still call it "problem" and only the few woke people will call it "bugaboo".
• I can foresee that somewhere in the future, some Legendary Grandmaster might write a blog saying that people who say "bugaboo" have high ratings and people who say "question" or "problem" don't. So this solution, isn't really a solution at all... It'll just cause even more problems(or more bugaboos idk).
• Lastly, and this one is the only actual valid reason (and also the only reason that was required): IT IS EXTREMELY CONFUSING to the newcomers, they have no clue what all this means. I agree it's extremely hilarious and I appreciate it, but most of us (except maybe a few geneosities) are at least 10 years old! And this type of a joke HAS TO get old someday or the other.

• +391

By HealthyUG, history, 7 months ago,

When I submit a problem from the problemset, I see the status with "my only" enabled(That is, I only see my own submissions). But from there if I try to go to the second or third page, then the "my only" flag gets auto disabled and I start seeing everyone's submissions.

I believe the bug must be easy to fix as the only mistake is that ?my=on should be present in the links that take us to other pages of the status.

The issue

• +134

By HealthyUG, 8 months ago,

I have a youtube channel on which I mainly do Hindi content and I had plans to do some Hindi live streams. Now I'm wondering is it ok if I embed them to CF because I became red yesterday and now this feature is available to me.

I know that it won't be relevant to a lot of people because of not being in English, that's why I'm asking before posting it there. Is it ok if I post about non-english streams?

• +130

By HealthyUG, history, 11 months ago,

EDIT: As I'll be posting a lot of videos in this series, instead of writing a separate blog everytime, I'll just keep on adding the links on this blog itself

Here are the links of the videos currently available in the DP playlist on my channel.

I'll add the remaining editorials soon, keep checking the blog regularly if you're interested. Also do give me suggestions, if you want such series on some other topic.

If you have any doubts/feedback/suggestions, comment them here or on the youtube video.

Original Text of the blog:-

• +78

By HealthyUG, history, 12 months ago,

LATEST EDIT: The channel is created, read more in my new blog.

EDIT: I have decided I'm going to start the channel. If you want videos on some specific topics or editorials of some famous questions, please mention them in the comment section below.

Hello everyone,

I see a lot of content in russian or chinese language that gets translated or rewritten in english and then it gets introduced to the world. I believe that in my country (India), there are people who aren't very familiar with English either. I actually know a few people who are sometimes unable to understand blogs and editorials because of being weak in English. Even some of the people who understand English pretty well might feel more comfortable with Hindi.

Now I know that English is a pretty standard language and people should be good at it, but I still believe that Hindi videos would actually be helpful to some people, although I'm not very sure, that's why I wrote this blog.

Should I start a youtube channel in which I make videos about algorithms and/or problem solutions in Hindi? I have a few nice topics in mind.

• +162

By HealthyUG, history, 15 months ago,

I was implementing a Trie for Google Kickstart earlier today and the code is malfunctioning in a very strange way. I have no idea why this is happening. I narrowed down the problem in a few hours.

#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b)        for(int i=a;i<b;i++)

struct node{
int ends=0;
int child[26]={0};
};

vector<node> trie;
int makenode(){
trie.push_back(node());
int x=(int)trie.size() - 1;
cout<<x<<" ";
return x;
}

void insert(string &s,int root=0,int pos=0){
if(pos==(int)(s.size())){
trie[root].ends++;
return;
}
int next=s[pos]-'A';
if(!trie[root].child[next]){
// trie.push_back(node()); trie[root].child[next]=(int)trie.size()-1;    //THIS LINE WORKS FINE
trie[root].child[next]=makenode();
cout<<trie[root].child[next]<<"\n";
}
insert(s,trie[root].child[next],pos+1);
}

int main(){
trie.clear();
trie.push_back(node());
string s;
cin>>s;
insert(s);
return 0;
}


The function makenode() returns x. When I print x, the values are fine but after returning the values are getting changed.

One would expect the above code to print the same integers per line but the values aren't same.

These are the values of x before and after returning from the function makenode().

Does anybody have any idea why this is happening?

(I have noticed that only the values 1,2,4,8,16,32,etc are wrong)

• +29

By HealthyUG, history, 15 months ago,

There's another simple greedy solution to the problem using dfs trees.

First form a dfs tree of the graph with any vertex as its root. Now consider a vertex $P$ which has a backedge to vertex $Q$, if $depth(P)-depth(Q)+1 >= \lceil\sqrt{n}\rceil$ then we have found a cycle of at least $\lceil\sqrt{n}\rceil$ vertices.

If we cannot find such a cycle, we'll find an independent set, we know that the leaves of a dfs tree do not have an edge between them. So we'll take all the leaves in the independent set. But that may not be enough we need more vertices, so we'll choose each such vertex whose depth is at least $\left(\lceil\sqrt{n}\rceil - 1\right)$ less than the minimum depth of all the chosen vertices in it's subtree and insert it to the independent set (we can do so because if there is an edge between the current vertex and any of the previously chosen vertices, we would have found a cycle). How can we say that such an independent set will have at least $\lceil\sqrt{n}\rceil$ vertices? Here is an intuitive proof:-

Consider any linear chain in the dfs tree of length $L$ which terminates at a single leaf, we can pick $\lceil\frac{L}{\sqrt{n}}\rceil$ vertices from this chain. Whenever we put a vertex in the independent set, we can disconnect its entire subtree from the graph and consider it as a new leaf. After this we can select any other linear chain and repeat this process.

In total, we'll have $\sum{\lceil\frac{L}{\sqrt{n}}\rceil}$ vertices in our independent set which is at least $\lceil\frac{n}{\sqrt{n}}\rceil = \lceil\sqrt{n}\rceil$ (since $\sum{L} = n$).

I'd appreciate if someone can come up with a more concrete proof.

Here is my accepted solution: https://codeforces.com/contest/1325/submission/73328247