As a tester, I highly recommend everyone to participate <3

Why did you put a Div.4 contest on Tuesday? It would be better if it was on let's say, Sunday because Div.4 contests always have a ton of participants. This way a lot of people won't be able to participate because of their obligations.

And virtual participation is just not the same as live participation because you can see how many people solved each problem till the end of the contest, solutions etc.

I am not writing this because I am mad because I won't be able to participate in the contest (in fact, I will be able to participate) but because a lot of people won't participate because the contest is on Tuesday.

MikeMirzayanov or whoever decides the day of the contest

Strange. Why all of the commments are downvoted???

Expecting some intresting problems

As a tester, I don't like sausages.

Div 4 arrives... Every Specialist be like: First unrated contest for me!

My first unrated contest

:(

As

a tester, mesanu should add me in this blogpost.

What's wrong with the people who are downvoting every single comment? Is everyone supposed to not like these rounds just because you don't? This community is weird

Particularly liked the part about urging people not to register new accounts solely for narcissistic purposes =)

Damnn! 5000+ unrated accounts are participating in this contest, isn't a huge number? what do you say?

Is the starting time changed?

Any reason for delay of 15 minutes?

Why contest postponed?

Hope at least today I won't see the grid.

My first coding competition ever! Kinda excited

As a tester (I really tested it tonight!) I updated the post with the following text:

The opinions of testers about the order of problems are very contradictory. Please do not rely heavily on the order of problems in the round and read all the problems. Good luck!

Thank you for this contest!

Favourite problem is E it is simple to understand, but it isn't easy.

Nice Contest!

Wtf problem F sick implementation?!Stop proposing this kind of problems!

how to solve E?

Contest was fun and tasks were great. Thank you for this Div4!

if anyone is interested, I recorded myself doing all problems

if only for E it was hs<=hi<=hsb and ws<=wi<=wb, it would have been so much easier, well anyway can someone give me a hint, i stored areas of all rectangles , sorted them , stored prefix sum array, then searched idx_left=upper_bound(hs*ws) and idx_right=lower_bound(hb*wb)-1 on sorted areas, then got the sum with the perfix sum array, can i tweak this to fit the hs<hi<hsb and ws<wi<wb constraints? also brute force gave me TLE X_X

Why this code got runtime error at test 8?

https://codeforces.com/contest/1722/submission/170265006

I found F easier than E. The time limit of 6 seconds on E allowed my O(q*1000*logn) solution to pass.

What is the point of $$$\mathrm{TL} = 6 \,\mathrm{s}$$$ in the problem E? To make stupid brute-force solution pass?

I was so close to solving 1722G - Even-Odd XOR (or I at least think so)! Can anybody please explain to me how to solve it?

when codeforces post its contest editorial ?

Can anyone explain the error in my submission?170267520

Can someone hack my solution for problem G. I think my answer might generate duplicate numbers. Link

For the problem D i thought of using prefix sum. I was not able to implement it. What you guys did for problem D?

I think D can be done with dp. Here is my solution:

Every next answer is sum of previous answer and max points we can get by changing side of looking of some person. So ans[0] is score that we have in start. Max points we can add is actually biggest difference between points we can get from one person by its current looking and other side looking. So we can just make difference and sort it.

Here is code for my submission: https://codeforces.com/contest/1722/submission/170308742

can someone please explain how to do E?hints please?

Why did my code gave WA test 2 on E?

https://codeforces.com/contest/1722/submission/170276269

Edit i saw it =(

Can someone hack my solution of G?

I randomly fill an array with N-2 numbers and then just add two numbers to make XOR's equal. If I fail (i.e. needed number already in the array), I randomly fill the array again.

https://codeforces.com/contest/1722/submission/170260049

.....

Can anyone Explain Problem D? I used two pointer and greedy approach but don't know why is it failing for some test cases?

Here is my code

Code:

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define loop(i,a,b) for(ll i=a;i<b;i++)
#define range(a)    a.begin(),a.end()
#define p(a)        push_back(a)
#define mp          make_pair 
#define pqb             priority_queue<int>
#define pqs             priority_queue<int,vi,greater<int> >
#define w(x)            ll x; cin>>x; while(x--)
#define tr(it, a) for(auto it = a.begin(); it != a.end(); it++)
#define mii    map<int, int>    
#define umii   unordered_map<int, int>    
#define mll    map<ll, ll>    
#define umll   unordered_map<ll, ll>
#define pii    pair<int, int>    
#define pl     pair<ll, ll>
#define vi     vector<int>    
#define vl      vector<ll>    
#define si      set<int>    
#define sl      set<ll>    
#define vpii     vector<pii>    
#define vpl      vector<pl>    
#define vvi       vector<vi>    
#define  vvl       vector<vl>
#define fastinout ios_base::sync_with_stdio(false);cin.tie(NULL); cout.tie(NULL);    
#define MOD 1000000007
ll binExpIter(ll a,ll b,ll mod){long long ans=1;while(b>0){if(b&1){ans=(ans*a)%mod;}a=(a*a)%mod;b>>=1;}return ans;}
ll gcd(ll a, ll b) {if (b > a) {return gcd(b, a);} if (b == 0) {return a;} return gcd(b, a % b);}
ll phin(ll n) {ll number = n; if (n % 2 == 0) {number /= 2; while (n % 2 == 0) n /= 2;} for (ll i = 3; i <= sqrt(n); i += 2) {if (n % i == 0) {while (n % i == 0)n /= i; number = (number / i * (i - 1));}} if (n > 1)number = (number / n * (n - 1)) ; return number;} //O(sqrt(N))
vector<ll> sieve(int n) {int*arr = new int[n + 1](); vector<ll> vect; for (int i = 2; i <= n; i++)if (arr[i] == 0) {vect.push_back(i); for (int j = 2 * i; j <= n; j += i)arr[j] = 1;} return vect;}


//************************************//
int main(){
   w(t){
      ll n;
      cin>>n;
      string s;
      cin>>s;
      int x=0;
      int y=n-1;
      for(int i=1;i<=n;i++){
         int c=0;
         int ans=0;
         while(x<=y){
            if(s[x]=='L'){
               s[x]='R';
               c++;
            }
            if(c==i){
               break;
            }
            if(s[y]=='R'){
               s[y]='L';
               c++;
            }
            if(c==i){
               break;
            }
            x++;
            y--;
         }
         for(int k=0;k<n;k++){
            if(s[k]=='L'){
               ans+=k;
            }
            else{
               ans+=(n-1-k);
            }
         }
         cout<<ans<<" ";
         
      }
      cout<<endl;
   } 
}

Today is Hacking day

Is there problems with hacking process, no one unable to hack this user for the same problem and it still in queue state?

Too weak pretest for A. :(

Can D done with prefix sum?

Hello everyone my solution for 1 problem is accepted during contest but now it's shows its hack and solution is wrong?? What is mean I didn't get. Can you please tell how I got my solution correct.

Mize orz!!

Can we have rating change quickly please

is it unrated?

Attention! Your solution 170296922 for the problem 1722G significantly coincides with solutions Gaurav__Arora/170273818, om_arsa_2312/170279944, nihal_gupta/170293955, AhmedEl-Gohary/170296922. Such a coincidence is a clear rules violation. Note that unintentional leakage is also a violation. For example, do not use ideone.com with the default settings (public access to your code). If you have conclusive evidence that a coincidence has occurred due to the use of a common source published before the competition, write a comment to post about the round with all the details. More information can be found at http://codeforces.com/blog/entry/8790. Such violation of the rules may be the reason for blocking your account or other penalties. In case of repeated violations, your account may be blocked.

So my evidence that I didn't cheat or communicate with any one in the round is that i used a pre-written blog on geeks for geeks about finding an array of size n whose xor value is some k and I adjusted that function to solve yesterday's DIV4 G, you can take a look at my submission and compare for yourself.

https://www.geeksforgeeks.org/find-n-distinct-numbers-whose-bitwise-xor-is-equal-to-k/

I have got a system message that my solution coincides with some other participant's solution for the question G, and as asked I am presenting here the common source published before the competition.

https://www.geeksforgeeks.org/find-n-distinct-numbers-whose-bitwise-xor-is-equal-to-k/

As I had seen this post earlier on geeks for geeks, I simply used it.

Please consider my participation for this contest.

I have picked a portion of my code from an article of gfg: (https://www.geeksforgeeks.org/find-n-distinct-numbers-whose-bitwise-xor-is-equal-to-k/) You can verify the same. Please look into this and consider my participation. MikeMirzayanov

Why ratings are still not updated?

Was this round declared unrated?

I checked quite a few profiles from the comments and this round is marked as unrated for every single of those I checked. Any updates?

I have got a system message that my solution coincides with some other participant's solution for the question G, and as asked I am presenting here the common source published before the competition.

https://www.geeksforgeeks.org/program-binary-decimal-conversion/ Also used previosuly posted gfg function of binary to decimal conversion. As I had seen this post earlier on geeks for geeks, I simply used it.

Please consider my participation for this contest. Thank You

Hello I've got a system message that my submission to problem G coincides with some participants, but I've used the code present on GFG link to the GFG article Kindly consider my participation in this round. Thank You.

I have got a system message that my solution coincides with some other participant's solution for the question G, and as asked I am presenting here the common source published before the competition.

https://www.geeksforgeeks.org/find-n-distinct-numbers-whose-bitwise-xor-is-equal-to-k/

I have even put the link above in my submission. So please revert the decision.

why is the rating update taking so long?

Your solution 170295384 for the problem 1722G significantly coincides with solutions Jeopardy_007/170181586, kshitijsabale/170235981, pravin_as/170236185, sksusha8853/170244580, daijoub_dattebayo/170253614, Ag.akhand29Dec/170260220, vipin/170268963, coomlhamdle/170268986, no-one/170270439, pritish_001/170280715, vamshikrishna7697/170283391, saranshgoel_20/170287297, O_QufaD/170287888, noozy/170289556, noob5367/170290799, anurag78_20/170293266, CodeR_SaaD/170294427, singham_20/170294546, anupam_singh20/170295384, blablablacksheep/170295836, abhirai24/170297702, xorhero_02/170299463. Such a coincidence is a clear rules violation. Note that unintentional leakage is also a violation. For example, do not use ideone.com with the default settings (public access to your code). If you have conclusive evidence that a coincidence has occurred due to the use of a common source published before the competition, write a comment to post about the round with all the details. More information can be found at http://codeforces.com/blog/entry/8790. Such violation of the rules may be the reason for blocking your account or other penalties. In case of repeated violations, your account may be blocked.

Hello! This question had a similar logic as https://www.geeksforgeeks.org/find-n-distinct-numbers-whose-bitwise-xor-is-equal-to-k/, which means the code was published before the round, so I thought to use it. I think that the coincidence has occurred due to the use of a common source published before the competition. I don't even know any of the person's mentioned above. Is it a violation of rules, if it isn't then I request you to please look into this and resolve this. Thank You

@MikeMirzayanov Why only I got the penalty, and not everyone, while no one else got it Only my rating became negative

Me looking at my code for F after getting it accepted. (170379863)