Submission #498027

#	Time	Username	Problem	Language	Result	Execution time	Memory
498027		andrei_boaca	Fancy Fence (CEOI20_fancyfence)	C++17	100 / 100	75 ms	22752 KiB

fancyfence

#include <bits/stdc++.h>

using namespace std;
/*ifstream fin("date.in");
ofstream fout("date.out");*/
typedef long long ll;
const ll mod=1e9+7;
ll s[500005],st[500005],dr[500005],rmq[500005][22],n,loga[500005],ans;
struct date
{
    ll h,w;
} v[500005];
ll getmin(ll l, ll r)
{
    ll lg=r-l+1;
    ll lgr=loga[lg];
    return min(rmq[l][lgr],rmq[r-(1<<lgr)+1][lgr]);
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cin>>n;
    for(int i=1;i<=n;i++)
        cin>>v[i].h;
    for(int i=1;i<=n;i++)
    {
        loga[i]=loga[i-1];
        while((1LL<<(loga[i]+1))<=i)
            loga[i]++;
    }
    v[0].h=2e9;
    v[n+1].h=2e9;
    for(int i=1;i<=n;i++)
    {
        cin>>v[i].w;
    }
    for(int i=1;i<=n+1;i++)
        s[i]=s[i-1]+v[i].w;
    for(int i=n+1;i>=0;i--)
    {
        rmq[i][0]=v[i].h;
        for(int j=1;j<=17;j++)
            rmq[i][j]=min(rmq[i][j-1],rmq[i+(1<<(j-1))][j-1]);
    }
    for(int i=1;i<=n;i++)
    {
        int st=0;
        int dr=i-1;
        int pozmin=i,pozmax=i;
        while(st<=dr)
        {
            int mij=(st+dr)/2;
            ll val=getmin(mij,i-1);
            if(val>v[i].h)
            {
                pozmin=min(pozmin,mij);
                dr=mij-1;
            }
            else
                st=mij+1;
        }
        st=i+1;
        dr=n+1;
        while(st<=dr)
        {
            int mij=(st+dr)/2;
            ll val=getmin(i+1,mij);
            if(val>=v[i].h)
            {
                pozmax=max(pozmax,mij);
                st=mij+1;
            }
            else
                dr=mij-1;
        }
        ll chooseH=v[i].h*(v[i].h+1)/2LL;
        chooseH%=mod;
        // both outside

        ll nrL=s[i-1]-s[max(0,pozmin-1)];
        nrL%=mod;
        ll nrR=s[pozmax]-s[i];
        nrR%=mod;
        ll val=(nrL*nrR)%mod;
        val=(val*chooseH)%mod;
        ans=(ans+val)%mod;

        // left outside

        nrL=s[i-1]-s[max(0,pozmin-1)];
        nrL%=mod;
        nrR=v[i].w%mod;
        val=(nrL*nrR)%mod;
        val=(val*chooseH)%mod;
        ans=(ans+val)%mod;

        // right outside

        nrL=v[i].w%mod;
        nrR=s[pozmax]-s[i];
        nrR%=mod;
        val=(nrL*nrR)%mod;
        val=(val*chooseH)%mod;
        ans=(ans+val)%mod;

        // none outside

        ll chooseW=v[i].w*(v[i].w+1)/2LL;
        chooseW%=mod;
        val=(chooseH*chooseW)%mod;
        ans=(ans+val)%mod;
    }
    cout<<ans;
    return 0;
}

• Subtask 1: 0 / 0
• Subtask 2: 12 / 12
• Subtask 3: 13 / 13
• Subtask 4: 15 / 15
• Subtask 5: 15 / 15
• Subtask 6: 18 / 18
• Subtask 7: 27 / 27