atcoder_official's blog

By atcoder_official, history, 15 months ago, In English

We will hold AtCoder Beginner Contest 391.

We are looking forward to your participation!

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15 months ago, hide # |
 
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The first AtCoder race in this lunar year!

Good luck!

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15 months ago, hide # |
 
Vote: I like it +25 Vote: I do not like it

this contest was brutal

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15 months ago, hide # |
 
Vote: I like it +7 Vote: I do not like it

Is F some kind of a well-known problem or it's just really simple? Didn't solve it, but 1k+ submissions is quite a lot for F.

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15 months ago, hide # |
Rev. 3  
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Is D really so easy to implement? I keep getting WA on 21 testcases :(

Help me out please. Where am I going wrong? Submission

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    15 months ago, hide # ^ |
     
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    This fact simplifies the implementation significantly:

    Spoiler
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15 months ago, hide # |
 
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So ,is rank 1 legit?

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Why does everyone think E is easier than D but I do not think so?

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    15 months ago, hide # ^ |
     
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    For me, E is a simple divide and conquer problem. But I didn't bother to try D despite having 1 hour left, because of its complexity.

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15 months ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

G seems like a too well known problem for 200+ submissions.

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    15 months ago, hide # ^ |
     
    Vote: I like it +26 Vote: I do not like it

    I went through all of the Indian Submissions and almost all seem AI generated. Hopefully the admins take strict action.

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      15 months ago, hide # ^ |
       
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      Yeah I realised that when I saw low rated people solving G within 20 minutes and most of my friends not being able to solve it.

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15 months ago, hide # |
Rev. 2  
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why is the editorial of problem D with complexity O(n log n)? it can be solved in O(n)

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    15 months ago, hide # ^ |
     
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    as for the code:

    with complexity O(n+q)

    #include<bits/stdc++.h>
    using namespace std;
    const int N=2e5+10;
    struct block{
        int x,y;
    }a[N];
    int n,w,q;
    int id[N],idx[N],cnt[N],tl[N];
    int main(){
        ios::sync_with_stdio(false);
        cin.tie(NULL),cout.tie(NULL);
        cin>>n>>w;
        for(int i=1;i<=n;++i){cin>>a[i].x>>a[i].y;}
        cin>>q;
        for(int i=1;i<=n;++i){
            id[a[i].x]++;
            idx[i]=id[a[i].x];
            cnt[id[a[i].x]]++;
            tl[id[a[i].x]]=max(a[i].y,tl[id[a[i].x]]);
        }
        while(q--){
            int t,pos;
            cin>>t>>pos;
            if(cnt[idx[pos]]!=w){cout<<"Yes\n";}
            else{
                if(t<tl[idx[pos]]){cout<<"Yes\n";}
                else{cout<<"No\n";}
            }
        }
        return 0;
    }
    

    in fact, we don't need to sort

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15 months ago, hide # |
Rev. 2  
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Hey i have a question. I have heard lots of people talk about how good the ABCs are ? Can anyone tell me why they are good ? Thanks. I am a newbie so dont know a lot of stuff

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15 months ago, hide # |
 
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How to do E ?