Submission #1247411

#	Time	Username	Problem	Language	Result	Execution time	Memory
1247411		ulvix	Feast (NOI19_feast)	C++20	30 / 100	21 ms	2632 KiB

feast

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

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];
    }

    // Case K = 1: maximum subarray sum (with empty allowed)
    if (K == 1) {
        ll max_ending = 0;
        ll max_so_far = 0;
        for (ll x : A) {
            max_ending = max<ll>(0, max_ending + x);
            max_so_far = max(max_so_far, max_ending);
        }
        cout << max_so_far << "\n";
        return 0;
    }

    // Extract positive runs and gaps between them
    vector<ll> runs;
    vector<ll> gaps;
    int i = 0;
    while (i < N) {
        // Skip non-positives
        while (i < N && A[i] <= 0) {
            i++;
        }
        if (i >= N) break;
        // Collect positive run
        ll sumP = 0;
        while (i < N && A[i] > 0) {
            sumP += A[i];
            i++;
        }
        runs.push_back(sumP);
        // Collect the gap (negatives) until next positive
        ll sumG = 0;
        int j = i;
        while (j < N && A[j] <= 0) {
            sumG += A[j];
            j++;
        }
        if (j < N) {
            gaps.push_back(sumG);
        }
        i = j;
    }

    int M = runs.size();
    ll sumPos = 0;
    for (ll v : runs) sumPos += v;

    // If we have at least as many people as positive runs,
    // we can assign each run to someone (others empty)
    if (K >= M) {
        cout << sumPos << "\n";
        return 0;
    }

    // Need to merge (M-K) pairs by bridging across the least bad gaps
    sort(gaps.begin(), gaps.end(), greater<ll>());
    ll loss = 0;
    int merges = M - K;
    for (int t = 0; t < merges; t++) {
        loss += gaps[t];
    }

    cout << (sumPos + loss) << "\n";
    return 0;
}

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 0 / 10
• Subtask 5: 0 / 11
• Subtask 6: 0 / 20
• Subtask 7: 0 / 29