Submission #1268335

#	Time	Username	Problem	Language	Result	Execution time	Memory
1268335		nadeshiko	Lasers (NOI19_lasers)	C++20	100 / 100	268 ms	16824 KiB

lasers

#include <bits/stdc++.h>

using namespace std;

int main()
{
    long long Len,r;
    cin>>Len>>r;
    vector<pair<long long,long long>>ev;
    for(int j=0; j<r; j++)
    {
        long long n;
        cin>>n;
        vector<long long>a(n);
        for(int i=0; i<n; i++)cin>>a[i];
        vector<long long>pref(n+1,0);
        vector<long long>suff(n+2,0);
        for(int i=1; i<=n; i++)
        {
            pref[i]=pref[i-1]+a[i-1];
        }
        for(int i=n; i>=1; i--)
        {
            suff[i]=suff[i+1]+a[i-1];
        }
        //for(int i=1;i<=n;i++)cout<<pref[i]<<' '<<suff[i]<<'\n';
        for(int i=1; i<=n; i++)
        {
            long long x=pref[i];
            long long y=Len-suff[i]+1;
            if(x>=y)
            {
                long long l=y;
                long long rpos=x;
                if(l<1) l=1;
                if(l<=rpos)
                {
                    ev.push_back({l,1});
                    ev.push_back({rpos+1,-1});
                }
            }
        }
    }
    long long ans=0;
    long long pre=0;
    long long m=ev.size();
    sort(ev.begin(),ev.end());
    for(int i=0;i<m;i++){
        auto [x,sign]=ev[i];
        pre+=sign;
        if(pre>0){
            ans+=(i+1<m?ev[i+1].first-x:Len-x+1);
        }
    }
    cout<<ans;
}

• Subtask 1: 10 / 10
• Subtask 2: 14 / 14
• Subtask 3: 20 / 20
• Subtask 4: 21 / 21
• Subtask 5: 22 / 22
• Subtask 6: 13 / 13