Submission #890654

#	Time	Username	Problem	Language	Result	Execution time	Memory
890654		arbuzick	Let's Win the Election (JOI22_ho_t3)	C++17	61 / 100	2582 ms	821352 KiB

Main

#pragma GCC optimize("O3")
#include <bits/stdc++.h>

using namespace std;

constexpr int maxn = 501, inf = 1e9 + 7;

constexpr double eps = 1e-4;

double dp[maxn][maxn][maxn];

double get_ans(int n, int k, vector<double> &a, vector<pair<double, int>> &s_b, int cnt_all) {
    for (int i = 0; i <= n; ++i) {
        for (int cnt_nw = 0; cnt_nw <= i && cnt_nw <= cnt_all; ++cnt_nw) {
            for (int cnt_used = 0; cnt_used <= k; ++cnt_used) {
                dp[i][cnt_nw][cnt_used] = inf;
            }
        }
    }
    dp[0][0][0] = 0;
    double ans = inf;
    for (int i = 0; i < n; ++i) {
        for (int cnt_nw = 0; cnt_nw <= i && cnt_nw <= cnt_all; ++cnt_nw) {
            for (int cnt_used = 0; cnt_used < k; ++cnt_used) {
                if (s_b[i].first < 10000 && cnt_nw < cnt_all) {
                    dp[i + 1][cnt_nw + 1][cnt_used + 1] = min(dp[i + 1][cnt_nw + 1][cnt_used + 1], dp[i][cnt_nw][cnt_used] + s_b[i].first / (cnt_nw + 1));
                    if (cnt_used + 1 == k && cnt_nw + 1 == cnt_all) {
                        ans = min(ans, dp[i + 1][cnt_nw + 1][cnt_used + 1]);
                    }
                }
                dp[i + 1][cnt_nw][cnt_used + 1] = min(dp[i + 1][cnt_nw][cnt_used + 1], dp[i][cnt_nw][cnt_used] + a[s_b[i].second] / (cnt_all + 1));
                if (cnt_used + 1 == k && cnt_nw == cnt_all) {
                    ans = min(ans, dp[i + 1][cnt_nw][cnt_used + 1]);
                }
                dp[i + 1][cnt_nw][cnt_used] = min(dp[i + 1][cnt_nw][cnt_used], dp[i][cnt_nw][cnt_used]);
            }
        }
    }
    return ans;
}

void solve() {
    int n, k;
    cin >> n >> k;
    vector<double> a(n), b(n);
    vector<pair<double, int>> s_b;
    for (int i = 0; i < n; ++i) {
        cin >> a[i] >> b[i];
        if (b[i] > 0) {
            s_b.emplace_back(b[i], i);
        } else {
            s_b.emplace_back(inf, i);
        }
    }
    sort(s_b.begin(), s_b.end());
    double ans = inf, ans_prv = inf;
    for (int cnt_all = 0; cnt_all < k; ++cnt_all) {
        ans = min(ans, get_ans(n, k, a, s_b, cnt_all));
        if (abs(ans - ans_prv) < eps) {
            break;
        }
        ans_prv = ans;
    }
    cout << ans << '\n';
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.precision(25);
    cout << fixed;
    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 0 / 5
• Subtask 3: 11 / 11
• Subtask 4: 12 / 12
• Subtask 5: 33 / 33
• Subtask 6: 0 / 11
• Subtask 7: 0 / 23