Submission #644264

#	Time	Username	Problem	Language	Result	Execution time	Memory
644264		Itamar	Fancy Fence (CEOI20_fancyfence)	C++14	25 / 100	19 ms	4564 KiB

fancyfence

// CEOI.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>
using namespace std;
#define ll long long
#include <vector>
#define vll vector<ll>
const int m = 1e9 + 7;
ll c(ll x) {
    return ((x * (x - 1)) / 2) % m;
}

int main()
{
    int n;
    cin >> n;
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    vll resh(n + 2);
    vll h(n+2);
    for (int i = 0; i < n; i++) {
        int hi;
        cin >> hi;
        h[i + 1] = hi;
    }
    for (int i = 0; i < n; i++) {
        int w;
        cin >> w;
        resh[i + 1] = (resh[i] + w)%m;
    }
    vll v;
    vll l(n+2);
    vll r(n+2);
    for (int i = 0; i < n+2; i++) {
        while (!v.empty() && h[v.back()] > h[i]) {
            r[v.back()] = i;
            v.pop_back();
        }
        v.push_back(i);
    }
    for (int i = n+1; i >=0; i--) {
        while (!v.empty() && h[v.back()] >= h[i]) {
            l[v.back()] = i;
            v.pop_back();
        }
        v.push_back(i);
    }
    ll ans=0;
    for (int i = 1; i <= n; i++) {
        ans = (ans + c(h[i]+1)*((resh[i] - resh[l[i]]) * (resh[r[i] - 1] - resh[i - 1]))%m) % m;
        ans = (ans - c(resh[i] - resh[i - 1] ) * c(h[i] + 1)) % m;
    }
    if (ans < 0)
        ans += m;
    cout << ans;
}

// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

// Tips for Getting Started: 
//   1. Use the Solution Explorer window to add/manage files
//   2. Use the Team Explorer window to connect to source control
//   3. Use the Output window to see build output and other messages
//   4. Use the Error List window to view errors
//   5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
//   6. In the future, to open this project again, go to File > Open > Project and select the .sln file

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