제출 #1228470

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1228470		Turkhuu	Fancy Fence (CEOI20_fancyfence)	C++20	100 / 100	15 ms	2244 KiB

fancyfence

#include <bits/stdc++.h>
#define FOR(i, a, b) for (auto i = (a); i <= (b); i++)
#define ROF(i, a, b) for (auto i = (a); i >= (b); i--)
using namespace std;
using ll = long long;
const int mod = 1e9 + 7, i2 = 500000004, i6 = 166666668;
int mul(int a, int b) {
    return 1LL * a * b % mod;
}
void add(int &a, int b) {
    if ((a += b) >= mod) a -= mod;
}
void sub(int &a, int b) {
    if ((a -= b) < 0) a += mod;
}
int f(int n) {
    return mul(i2, mul(n, n + 1)); 
} 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int N;
    cin >> N;
    vector<int> h(N), w(N); 
    for (int& x : h) cin >> x;
    for (int& x : w) cin >> x;
    int ans = 0, s = 0;
    vector<array<int, 2>> stk;
    for (int i = 0; i < N; i++) {
        add(ans, mul(f(h[i]), f(w[i])));
        int t = w[i];
        while (!stk.empty() && stk.back()[0] >= h[i]) {
            sub(s, mul(f(stk.back()[0]), stk.back()[1]));
            add(t, stk.back()[1]);
            stk.pop_back();
        }
        add(s, mul(f(h[i]), t));
        add(ans, mul(w[i], s));
        sub(ans, mul(f(h[i]), mul(w[i], w[i])));
        stk.push_back({h[i], t});
    }
    cout << ans << "\n";
    return 6/22;
}

• 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