I hope to get specialist in this contest, I have a high hope for it. And, BTW, is online class for the university avialiable?

The CSAI curriculum link leads to a deleted file.

As a tester, i recommend!

i have very bad track record with edu,hoping to get positive delta in this contest!

I hope it goes well

I hope after this round I feel some confident

pls postpone this contest by 2 hours I have doctor appointment

less go. another edu round :fire

why does all the edu rounds are authored by awoo and BledDest ??

and Neon too

another edu, hoping to get back to pupil

Is this competition has open hack?

i love edu round

Good luck to myself and all of you!

I hope I become pupil in this round!

I hope to educate in this round

As an unrated participant, good luck to all rated participants.

Div 2 haha

Again! gonna get down! :(

I love edu round in CF as like as messi in football :v

what about score distribution ?

i hope this contenst doesnt ->()(->)-> ->()(->)-> ->()(->)-> ->()(->)-> ->()(->)-> me

Hi everyone, could someone explain the differences between educational and regular contests?

aahhh. bad experience for me, cause swap n, m I took about 30-40 min on debuging.

ahhhh. bad experience for me. Cause swap n,m, I took about 30-40 min on debug. Wish less mistakes on next round.

GPTForces. Brutal, people who can't even solve A on their own are getting (A-C) now.

This will also screw up the problem ratings. Problems that would have been legitimate 1500-1700 will now be considered 1100-1200 due to these AI scammers.

Seems like all the cheaters that got banned from Leetcode have migrated here because they have worse cheat detection

AiForces

i think this round should be renamed to "Math & Combinatorics Round"

No way these many people were able to solve problem D, I suspect AI.

E made my head hurt; What's the solution?

MathForces :)

for E i figured out n<500, any more hints?

No way these many people solved problem D, I suspect AI.

Master finally! Thanks for great problems (especially E)!

C got me bad

I misread D as Your task is to calculate the probability that each cell is covered by at least one segment. instead of Your task is to calculate the probability that each cell is covered by exactly one segment.and wasted more than 1 hour:(( still happy because after a long time I will get positive delta in Edu

主播主播，这比赛很nb但还是太吃操作了，有没有那种即不吃操作又能上分的比赛 Streamer, this game is awesome, but it's still too skill-intensive. Are there any games that are neither skill-intensive nor hard to rank up in?

in problem 2,,,,

~~~~~~~~~~~~~~~~~~~~~~~~~~~~

include <bits/stdc++.h>

using namespace std;

int main() { int ;cin>>; while(_--){ int a,b,k; cin>>a>>b>>k; for(int i=2; i<=k; i++){ if(a<k && b<k){cout<< 1 <<endl;break;} else if(a/i <= k && b/i <= k && a%i==0 && b%i==0){cout<< 1 <<endl; break;} else{ cout<< 2 <<endl; break; } } }

}

~~~~~~~~~~~~~~~~~~~~~~~~ Why did this went wrong?

I was stuck with second question. Trying to conjur some way to get the minimum number of operations. After trying and failing for long. I had an ephiphany that other than a particular edge cases everything can be achieved with 2 operations. I had a feeling, I couldn't prove but as I already give 3 incorrect submissions. I tried and it passed. Not sure if this is good or bad.

How to E?

E is definitely NTT

from D to E is always hard to me

ABCD was posted on youtube 20 mins after the contest started, how am I supposed to compete?

I'm unable to figure out the issue in my code for D. Since contest is over, I didn't make any submission since it was failing test cases so I'll add it as context at the end.

Approach: Made a graph connecting r to l-1 with edge cost p/q (using modinv). Recursion is:

rec[i] += rec[j-1]*prob, where prob is choosing interval (j,i) with its probability and all other intervals ending at i are not chosen. So product of all 1-c, where c is edge cost, multiplied with cost of (j,i) divide the complement.

Not sure if the inverse handling is wrong, or the probability math, the recursion etc. It would be great some one could help debug this.

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define int long long
using ii = pair<int,int>;

int p = 998244353; // mp prime
vector<vector<ii>> g; // making a graph
int dp[200100];

int binpow(int a, int b){
    if(b==0) return 1;
    int res = 1;
    while(b){
        if(b&1) res = res*a%p;
        a = a*a%p;
        b>>=1;
    }

    return res;
}

int modinv(int n){
    return binpow(n,p-2);
}

int rec(int node){
    if(node==0) return 1; // base case

    if(dp[node]!=-1) return dp[node];

    int ans = 0;
    int cum_prob = 1;

    for(auto &pp: g[node]){
        int c = pp.first;
        int v = pp.second;
        cum_prob = cum_prob*((1-c+p)%p)%p;
    }

    for(auto &pp: g[node]){
        int c = pp.first;
        int v = pp.second;
        int prob = (cum_prob*c%p)*modinv((1-c+p)%p);
        ans = (ans + (prob*rec(v)%p))%p;
    }

    return dp[node] = ans;
}

void solve(){
    // Write solution here
    int n,m;
    cin >> n >> m;
    g.resize(m+1);
    memset(dp,-1,sizeof(dp));
    for(int i = 0;i<n;i++){
        int l,r,a,b;
        cin >> l >> r >> a >> b;
        g[r].push_back({a*modinv(b)%p, l-1}); // r connects to l-1 as r to l totally covered using edgw cost of p/q
    }

    cout << rec(m);
}

signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    solve();
}

Should have named variables better in retrospect...

Can someone link me the technique needed to do C? I dont know how to handle duplicate numbers that are divided by multiple primes less than 10