Submission #628722

#	Time	Username	Problem	Language	Result	Execution time	Memory
628722		Iwanttobreakfree	Fancy Fence (CEOI20_fancyfence)	C++17	30 / 100	91 ms	4472 KiB

fancyfence

#include <iostream>
#include <vector>
#include <map>
#include <stack>
using namespace std;
const int mod=1e9+7;
#define int long long
signed main(){
    int n;
    cin>>n;
    vector<int> v(n),h(n),pre(n+1);
    map<int,int> mp;
    for(int& i:h)cin>>i;
    for(int& i:v)cin>>i;
    for(int i=0;i<n;i++)pre[i+1]=(pre[i]+v[i])%mod;
    stack<pair<int,int>> st;
    st.push({0,n});
    vector<pair<int,int>> comp(n);
    for(int i=n-1;i>=0;i--){
        while(st.top().first>=h[i])st.pop();
        int dif=pre[st.top().second]-pre[i];
        if(dif<0)dif+=mod;
        comp[i]={h[i],dif};
        st.push({h[i],i});
    }
    int ans=0;
    for(int i=0;i<n;i++){
        pair<int,int> x=comp[i];
        //cout<<(1ll*x.first*(x.first+1)/2)<<' '<<(1ll*x.second*(x.second+1)/2)<<'\n';
        ans+=(((x.first*(x.first+1)/2)%mod)*((x.second*(x.second+1)/2)%mod))%mod;
        ans%=mod;
        if(i){
            pair<int,int> y=comp[i-1];
            ans-=(((y.first*(y.first+1)/2)%mod)*((x.second*(x.second+1)/2)%mod))%mod;
            if(ans<0)ans=((ans%mod)+mod)%mod;
        }
    }
    //cout<<(((1ll*(mod-7)*(mod-6)/2)%mod)*((1ll*(mod-7)*(mod-6)/2)%mod))%mod<<' ';
    cout<<ans;
}

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