Submission #1313955

#	Time	Username	Problem	Language	Result	Execution time	Memory
1313955		alansong	Feast (NOI19_feast)	C++20	100 / 100	245 ms	2616 KiB

feast

#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using i128 = __int128_t;

struct State {
    i128 val; 
    int cnt;  
};

static inline State bestState(const State& a, const State& b) {
    if (a.val != b.val) return (a.val > b.val) ? a : b;
    return (a.cnt > b.cnt) ? a : b;
}

static string to_string_i128(i128 x) {
    if (x == 0) return "0";
    bool neg = false;
    if (x < 0) { neg = true; x = -x; }
    string s;
    while (x > 0) {
        int digit = (int)(x % 10);
        s.push_back(char('0' + digit));
        x /= 10;
    }
    if (neg) s.push_back('-');
    reverse(s.begin(), s.end());
    return s;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N, K;
    cin >> N >> K;
    vector<ll> A(N);
    for (int i = 0; i < N; i++) cin >> A[i];

    ll posSum = 0;
    for (ll x : A) if (x > 0) posSum += x;

    auto solve = [&](ll lambda) -> State {
        const i128 NEG = -((i128)1 << 120);

        State out{0, 0};   
        State in{NEG, 0};   

        for (ll x : A) {
            State extend{in.val + (i128)x, in.cnt};
            State start{out.val + (i128)x - (i128)lambda, out.cnt + 1};

            State in2 = bestState(extend, start);

            State out2 = bestState(out, bestState(in, in2));

            out = out2;
            in = in2;
        }
        return bestState(out, in);
    };

    State st0 = solve(0);
    if (st0.cnt <= K) {
        cout << to_string_i128(st0.val) << "\n";
        return 0;
    }

    ll lo = 0, hi = posSum + 1; 
    while (lo < hi) {
        ll mid = lo + (hi - lo + 1) / 2;
        State st = solve(mid);
        if (st.cnt >= K) lo = mid;
        else hi = mid - 1;
    }

    ll lambda = lo;
    State st = solve(lambda);

    i128 ans = st.val + (i128)lambda * (i128)K;

    cout << to_string_i128(ans) << "\n";
    return 0;
}

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 11 / 11
• Subtask 6: 20 / 20
• Subtask 7: 29 / 29