Submission #823242

#	Time	Username	Problem	Language	Result	Execution time	Memory
823242		t6twotwo	Tortoise (CEOI21_tortoise)	C++17	48 / 100	3079 ms	382748 KiB

tortoise

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int N;
    cin >> N;
    vector<int> A(N);
    for (int i = 0; i < N; i++) {
        cin >> A[i];
    }
    vector<int> L(N, -1), R(N, N);
    for (int i = 0; i < N; i++) {
        if (A[i] == -1) {
            L[i] = i;
        } else if (i) {
            L[i] = L[i - 1];
        }
        int j = N - i - 1;
        if (A[j] == -1) {
            R[j] = j;
        } else if (i) {
            R[j] = R[j + 1];
        }
    }
    int ans = 0;
    vector dp(2 * N + 1, vector<int>(N, -1e9));
    dp[0][0] = 0;
    for (int i = 0; i < N; i++) {
        if (A[i] == -1) {
            continue;
        }
        auto pd = dp;
        for (int j = 0; j <= 2 * N; j++) {
            for (int k = 0; k < N; k++) {
                if (pd[j][k] < 0) {
                    continue;
                }
                for (int c = 1; c <= A[i]; c++) {
                    int t = 2 * (c - 1) * min(L[i] == -1 ? N : i - L[i], R[i] == N ? N : R[i] - i);
                    if (j + abs(i - k) + t > 2 * i) {
                        break;
                    }
                    ans = max(ans, pd[j][k] + c);
                    if (L[i] != -1) {
                        int p = j + abs(i - k) + t + i - L[i];
                        if (p <= 2 * N) {
                            dp[p][L[i]] = max(dp[p][L[i]], pd[j][k] + c);
                        }
                    }
                    if (R[i] != N) {
                        int p = j + abs(i - k) + t + R[i] - i;
                        if (p <= 2 * N) {
                            dp[p][R[i]] = max(dp[p][R[i]], pd[j][k] + c);
                        }
                    }
                }
            }
        }
    }
    ans = -ans;
    for (int i = 0; i < N; i++) {
        if (A[i] != -1) {
            ans += A[i];
        }
    }
    cout << ans << "\n";
    return 6/22;
}

• Subtask 1: 8 / 8
• Subtask 2: 10 / 10
• Subtask 3: 30 / 30
• Subtask 4: 0 / 25
• Subtask 5: 0 / 27