Submission #1188348

#	Time	Username	Problem	Language	Result	Execution time	Memory
1188348		NoMercy	Fancy Fence (CEOI20_fancyfence)	C++20	100 / 100	15 ms	3400 KiB

fancyfence

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

const ll mod = 1e9 + 7;

int32_t main () {

    ios_base::sync_with_stdio(0); 
    cin.tie(0); 
    cout.tie(0); 

    int N;
    cin >> N;
    vector<ll> h(N), w(N);
    for (int i = 0;i < N;i ++) cin >> h[i];
    for (int i = 0;i < N;i ++) cin >> w[i];

    ll sum = 0, res = 0;
    stack<array<ll, 2>> st;
    for (int i = 0;i < N;i ++) {
        ll cnt = w[i];
        while (st.size() > 0 && st.top()[0] >= h[i]) {
            cnt = (cnt + st.top()[1]) % mod;
            sum = (sum - (((st.top()[0] * (st.top()[0] + 1) / 2) % mod) * st.top()[1] % mod) + mod) % mod;
            sum = (sum + (((h[i] * (h[i] + 1) / 2) % mod) * st.top()[1] % mod)) % mod;
            st.pop();
        }
        st.push({h[i], cnt});
        res = (res + (sum * w[i] % mod) % mod);
        res = (res + (((h[i] * (h[i] + 1) / 2) % mod) * ((w[i] * (w[i] + 1) / 2) % mod) % mod)) % mod;
        sum = (sum + (((h[i] * (h[i] + 1) / 2) % mod) * w[i] % mod)) % mod;
        // cout << res << " " << sum << " " << cnt << "\n";
    }
    cout << res << "\n";
}

• 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