As a setter, I hope you like the contest.

Waiting

As a tester, shrek wishes you good luck.

hoping to see a good set of problems

Excited for contest

This contest will only take me 5 minutes to complete

Excited ✨✨

Prize pool is only for students? Not for working ones?

Can we fill regional centers choice after Prelims?

Slots of 400 is for 8 iits total or one iit 400 slots

₹10,00,000

Wtf is this number?

Is registration at https://iicpc.com only meant for students? I see a mandatory Graduation Year field which only provides options from 2025 to 2029 and another School option for under-university schooling students.

I will be able to participate directly on CodeChef Starters 173, but I didn't see any eligibility criteria mentioned for registration. I see a comment that only students are eligible for prizes. Please confirm on who should go for registration as well.

As a first-time tester, I hope you enjoy the problem set :)

As a setter (love that I can say this!), I hope you enjoy the problems :D

How are you going to make a combined rank list when div4 are supposed to do 3-4 extra problems than div1

As a organisor, I hope you have fun :)

Highlight the part of ranking system that this time it is icpc which is unusual, otherwise people will say again I didn't see that

Reminder: Contest starts in ~45 minutes — https://www.codechef.com/START173

Contest starts in ~30min.

It was a good idea to add the first problem as Time Penalty to make sure everyone knows there is a penalty for incorrect submissions. Appreciate the effort from authors.

where to see the leaderboard of all divisions ?

I got WA on test 12 in problem INTROVERTS

my idea was to achieve the main goal

void solve()
{
  int n;
  cin >> n;
  vec<int> a(n);
  for(auto &i: a)
    cin >> i;
  if(n <= 2)
  {
    cout << "YES";
    return;
  }
  if(a[0] + a[n - 1] != 3)
  {
    cout << "NO";
    return;
  }
  ordered_set<int> st;
  st.insert(1);
  st.insert(n);
  vec<int> pos(n + 1);
  for(int i = 0; i < n; i++)
    pos[a[i]] = i + 1;
  vec<bool> vis(n + 1, false);
  vis[1] = vis[n] = true;
  for(int i = 2; i < n; i++)
  {
    int p = pos[i + 1];
    if(vis[p])
    {
      cout << "NO";
      return;
    }
    int idx = st.order_of_key(p) - 1;
    assert(idx >= 0 and idx < SZ(st) - 1);
    int to = *st.find_by_order(idx + 1);
    int from = *st.find_by_order(idx);
    int len = to - from - 1;
    if(len & 1)
    {
      if(p != (to + from) / 2)
      {
        cout << "NO";
        return;
      }
    }
    else
    {
      int x = (to + from) / 2;
      int y = x + 1;
      if(p < x or p > y)
      {
        cout << "NO";
        return;
      }
    }
    vis[p] = true;
    st.insert(p);
  }
  cout << "YES";
}

I think the problem is that I didn't handle the case where I have to achieve the secondary goal, am I right ?, or there is something wrong with my approach to achieve the main goal ?

No Idea why my 2^n recursive solution for Cool checker Passes .. I just generated all the subsequences and stopped when i found a average not in B array .. But I thought It would give TLE when we have a big array with all same elements but surprisingly it passed .. I earlier was trying to do it with only distinct elements but it was giving WA (hence tried with all elements later)..

Hi, this it to inform that the Codechef compiler was judging INCORRECTLY during starters 173.

Kindly look into it as it ruins the contest experience. harshith_04

Do we need to have the same email id linked with the codechef account as the one used for registration?

Please use this form to report any suspicious codes you come across in the IICPC Codefest. If you believe a submission involves plagiarism, multiple accounts, AI-generated content, or any other form of unfair advantage, kindly fill out the details. Your reports will help us ensure fair competition.

https://forms.gle/yRSBRwWgErpteoXJA

Thank you for your cooperation!

When can we expect the final leaderboard?

Thanks for participating; results of Prelims can be found on https://iicpc.com/prelimsresults