Submission #1011505

#	Time	Username	Problem	Language	Result	Execution time	Memory
1011505		Rifal	Fancy Fence (CEOI20_fancyfence)	C++14	100 / 100	24 ms	5604 KiB

fancyfence

#include <bits/stdc++.h>
#include <fstream>
#define endl '\n'
#define mod 1000000007
#define INF 1000000000
#define INF2 2000000000000000000
//#define ll long long
///#define cin fin
///#define cout fout
using namespace std;
double const EPS = 1e-14;
///ofstream fout("herding.out");
///ifstream fin("herding.in");

int main()
{
    ios_base::sync_with_stdio(0);cout.tie(0);cin.tie(0);
    int n; cin >> n; long long h[n], w[n];
    for(int i = 0; i < n; i++) cin >> h[i];
    for(int i = 0; i < n; i++) cin >> w[i];
    stack<pair<long long, long long>> st;
    long long ans = 0, nw = 0;
    for(int i = 0; i < n; i++) {
         nw = 0;
        while(!st.empty() && st.top().first > h[i]) {
            pair<long long, long long> now = st.top();
            nw += now.second;
            nw %= mod;
            st.pop();
            ans += (((now.first*(now.first+1))/2%mod) * ((nw*(nw+1))/2%mod)%mod);
          //  cout << (((now.first*(now.first+1))/2%mod) * ((nw*(nw+1))/2%mod)%mod) << 'a' << endl;
            ans %= mod;
            if(!st.empty() && st.top().first > h[i]) {
                ans -= ((st.top().first*(st.top().first+1))/2%mod) * ((nw*(nw+1))/2%mod)%mod;
           //     cout << ((st.top().first*(st.top().first+1))/2%mod) * ((nw*(nw+1))/2%mod)  << 'b'<< endl;
                ans += mod;
                ans %= mod;
            }
            else {
                ans -= ((h[i]*(h[i]+1))/2%mod) * ((nw*(nw+1))/2%mod)%mod;
                ans += mod;
                ans %= mod;
            }
        }

        st.push({h[i],w[i]+nw});
       // cout << h[i] << ' ' << w[i]+nw << 's' << endl;
    }
    nw = 0;
        while(!st.empty()) {
            pair<long long, long long> now = st.top();
            nw += now.second;
            nw %= mod;
            st.pop();
            ans += (((now.first*(now.first+1))/2%mod) * ((nw*(nw+1))/2%mod)%mod);
           // cout << (((now.first*(now.first+1))/2%mod) * ((nw*(nw+1))/2%mod)%mod) << 'c' << endl;
            ans %= mod;
            if(!st.empty()) {
                ans -= ((st.top().first*(st.top().first+1))/2%mod) * ((nw*(nw+1))/2%mod)%mod;
              //  cout << ((st.top().first*(st.top().first+1))/2%mod) * ((nw*(nw+1))/2%mod)%mod << 'd' << endl;
                ans += mod;
                ans %= mod;
            }
        }
    cout << ans%mod << endl;
    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