Submission #1288173

#	Time	Username	Problem	Language	Result	Execution time	Memory
1288173		zyntherix	Fancy Fence (CEOI20_fancyfence)	C++20	100 / 100	18 ms	4164 KiB

fancyfence

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pi pair<int, int>
#define vi vector<int>
#define vs vector<string>
#define vb vector<bool>
#define vpi vector<pi>
#define pb push_back
#define all(a) (a).begin(), (a).end()
const int mod = 1e9 + 7;
int md_inv_2 = 500000004;

int sm(int x)
{
    return (((x * (x + 1)) % mod) * md_inv_2) % mod;
}

void solve()
{
    int n;
    cin >> n;
    int h[n + 1], w[n + 1];
    for (int i = 0; i < n; i++)
        cin >> h[i];
    for (int i = 0; i < n; i++)
    {
        cin >> w[i];
    }
    h[n] = 0;
    w[n] = 0;
    vpi v; // height, start_pos
    v.pb({0, 0});
    int ans = 0;
    int pos = 1;
    for (int i = 0; i <= n; i++)
    {
        int curr = pos;
        int gwi = 0;
        while (h[i] < v.back().first)
        {
            auto x = v.back();
            v.pop_back();
            int wi = (((curr - x.second) % mod) + mod) % mod;
            gwi = (gwi + wi) % mod;
            int hz = (((sm(x.first) - sm(h[i])) % mod) + mod) % mod;
            int vr = (((sm(gwi) - sm(gwi - wi)) % mod) + mod) % mod;
            ans = (ans + (hz * vr) % mod) % mod;
            curr = x.second;
        }
        if (h[i] > v.back().first)
        {
            v.pb({h[i], curr});
        }
        pos = (pos + w[i]) % mod;
    }
    cout << ans << '\n';
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);
    int t = 1;
    // cin >> t;
    while (t--)
    {
        solve();
    }
    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