제출 #337615

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
337615		ncduy0303	Discharging (NOI20_discharging)	C++17	100 / 100	129 ms	12000 KiB

Discharging

#include <bits/stdc++.h>

using namespace std;

#define ar array
#define ll long long

const int MAX_N = 1e5 + 1;
const ll MOD = 1e9 + 7;
const ll INF = 1e9;

struct convexhull {
    struct line {
        ll m, c; 
        line(ll m, ll c): m(m), c(c) {}
        ll operator()(ll x) {return m * x + c;}
    };
    deque<line> dq;
 
    bool bad(line a, line b, line c) {
        return 1.0 * (c.c - a.c) / (a.m - c.m) <= 1.0 * (b.c - a.c) /  (a.m - b.m);
    }
 
    void add(line l) {
        while(dq.size() > 1 && bad(dq[(int)dq.size() - 2], dq.back(), l))
            dq.pop_back();
        dq.emplace_back(l);
    }

    ll query(ll x) { // min query, increasing x
        while (dq.size() >= 2 && dq[0](x) >= dq[1](x)) dq.pop_front();
        return dq[0](x);
    }
 
    // ll query(ll x) { // min query, any x
    //     int lo = -1, hi = dq.size() - 1;
    //     while (lo + 1 < hi) {
    //         int mid = (lo + hi) / 2;
    //         if (dq[mid](x) >= dq[mid + 1](x)) lo = mid;
    //         else hi = mid;
    //     }
    //     return dq[hi](x);
    // }
};

// struct convexhull {
//     struct line {
//         ll m, c; 
//         line(ll m, ll c): m(m), c(c) {}
//         ll operator()(ll x) {return m * x + c;}
//     };
//     deque<line> dq;
//     bool check(line p1, line p2, line p3) {
//         return (p2.m - p1.m) * (p3.c - p2.c) >= (p3.m - p2.m) * (p2.c - p1.c);
//     }
//     void add(line y) { // decreasing slope
//         while (dq.size() >= 2 && check(dq[dq.size() - 2], dq[dq.size() - 1], y)) dq.pop_back();
//         dq.push_back(y);
//     }
//     ll query(ll x) { // min query, increasing x
//         while (dq.size() >= 2 && dq[0](x) >= dq[1](x)) dq.pop_front();
//         return dq[0](x);
//     }
//     ll query(ll x) { // min query, any x
//         int lo = -1, hi = dq.size() - 1;
//         while (lo + 1 < hi) {
//             int mid = (lo + hi) / 2;
//             if (dq[mid](x) >= dq[mid + 1](x)) lo = mid;
//             else hi = mid;
//         }
//         return dq[hi](x);
//     }
// };

void solve() {
    int n; cin >> n;
    vector<int> a(n + 1);
    for (int i = n; i > 0; i--) cin >> a[i];
    vector<int> st;
    for (int i = 1; i <= n; i++) {
        while (st.size() && a[st.back()] <= a[i]) st.pop_back();
        st.push_back(i);
    }
    int m = st.size();
    vector<ll> dp(m + 1);
    convexhull cht;
    for (int i = 1; i <= m; i++) {
        cht.add({a[st[i - 1]], dp[i - 1]});
        dp[i] = cht.query(st[i - 1]);
    }
    cout << dp[m] << "\n";
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    int tc = 1;
    // cin >> tc;
    for (int t = 1; t <= tc; t++) {
        // cout << "Case #" << t  << ": ";
        solve();
    }
}

• Subtask 1: 9 / 9
• Subtask 2: 13 / 13
• Subtask 3: 25 / 25
• Subtask 4: 11 / 11
• Subtask 5: 14 / 14
• Subtask 6: 28 / 28