Submission #414477

#	Time	Username	Problem	Language	Result	Execution time	Memory
414477		CrouchingDragon	Hacker (BOI15_hac)	C++17	100 / 100	78 ms	6876 KiB

hac

#include "bits/stdc++.h"

using namespace std;

#define endl '\n'
#define debug(x) cerr << #x << " == " << (x) << '\n';
#define all(x) begin(x), end(x)

using ll = long long;

const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3fLL;

template<typename T>
struct M1 {
    using Type = T;
    inline const static T Id = numeric_limits<T>::min();
    static T op(const T& x, const T& y) { return max(x, y); }
};

template<typename Monoid, bool top_down>
struct MinimumStack {
    using M = Monoid;
    using T = typename M::Type;
    stack<pair<T, T>> st;
    T top() const { return st.top().first; }
    T minimum() const { return st.empty() ? M::Id : st.top().second; }
    void push(T value) {
        st.emplace(value, top_down ? M::op(value, minimum()) : M::op(minimum(), value));
    }
    void pop() { st.pop(); }
    bool empty() const { return st.empty(); }
    size_t size() const { return size(st); }
};

template<typename Monoid>
struct MinimumQueue {
    using M = Monoid;
    using T = typename Monoid::Type;
    MinimumStack<Monoid, false> in;
    MinimumStack<Monoid, true> out;
    void move() {
        if (out.empty()) while (not in.empty()) {
            out.push(in.top());
            in.pop();
        }
    }
    T front() { move(); return out.top(); }
    T minimum() const { return M::op(out.minimum(), in.minimum()); }
    void push(T value) { in.push(value); }
    void pop() { move(); out.pop(); }
    bool empty() const { return in.empty() && out.empty(); }
    size_t size() const { return size(in) + size(out); }
};

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int n;
    cin >> n;

    vector<int> v(n);
    for (auto& x : v) cin >> x;

    MinimumQueue<M1<int>> mq;
    int sum = 0, cnt = n / 2;
    for (int i = 1; i < 1 + cnt; ++i) {
        sum += v[i];
    }
    mq.push(sum);
    for (int i = 1 + cnt; i < n; ++i) {
        sum += v[i] - v[i - cnt];
        mq.push(sum);
    }

    int opt = INF;
    for (int i = 0; i < n; ++i) {
        opt = min(opt, mq.minimum());
        mq.pop();
        sum += v[i] - v[(i + n - cnt) % n];
        mq.push(sum);
    }

    int ans = accumulate(all(v), 0) - opt;
    cout << ans << endl;

    exit(0);
}

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 40 / 40