Submission #1220346

#	Time	Username	Problem	Language	Result	Execution time	Memory
1220346		friendiks	Fancy Fence (CEOI20_fancyfence)	C++20	30 / 100	25 ms	4032 KiB

fancyfence

#ifndef LOCAL
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC diagnostic ignored "-Wpedantic"
#endif

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

auto seed = chrono::high_resolution_clock::now().time_since_epoch().count();
mt19937 rnd(52);
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename V>
using table = gp_hash_table<T, V>;

using i128 = __int128;
using ll = long long;
using ld = long double;
using uint = unsigned int;
using ull = unsigned long long;

const ll INF = 2e18;
const int inf = 1e9;
const int maxn = 1e5 + 7;
const int MOD = 1e9 + 7;
const ld pi = acos(-1);
const int P = 5167;
const int L = 26;
const ld EPS = 0.0005;
const ll K = 40;
const ll back2 = MOD / 2 + 1;

template<typename T, typename V>
void fill(T &container, V value) {
    for (auto &c : container)
        c = value;
}

#define int ll

int get1(int h, int w) {
    ll a = h * (h + 1) / 2;
    a %= MOD;
    return (a * (w % MOD)) % MOD;
}

int get2(int h, int w) {
    int a = h * w, b = h * w + h + w + 1;
    a %= MOD;
    b %= MOD;
    a = (a * back2) % MOD;
    b = (b * back2) % MOD;
    return (a * b) % MOD;
}

void solve() {
    int n;
    cin >> n;
    vector<int> h(n), w(n);
    for (int i = 0; i < n; ++i) cin >> h[i];
    for (int i = 0; i < n; ++i) cin >> w[i];
    int ans = 0;
    int cnt = 0;
    vector<pair<int, int> > st;
    for (int i = 0; i < n; ++i) {
        pair<int, int> curr = {h[i], 0};
        while (!st.empty() && st.back().first >= h[i]) {
            curr.second += st.back().second;
            cnt = (cnt - get1(curr.first, curr.second) + MOD) % MOD;
            st.pop_back();
        }
        st.push_back(curr);
        cnt += get1(curr.first, curr.second);
        cnt %= MOD;
        ans += cnt * w[i];
        ans %= MOD;
        cnt = (cnt - get1(curr.first, curr.second) + MOD) % MOD;
        st.back().second += w[i];
        cnt += get1(st.back().first, st.back().second);
        cnt %= MOD;
        ans %= MOD;
        ans += get2(h[i], w[i]);
        ans %= MOD;
    }
    cout << ans << "\n";
}

signed main() {
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(7);
    int t = 1;
    //cin >> t;
    while (t--) solve();
    //stress();
}

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