Submission #922069

#	Time	Username	Problem	Language	Result	Execution time	Memory
922069		cthbst	Let's Win the Election (JOI22_ho_t3)	C++14	10 / 100	1604 ms	2644 KiB

Main

#include <algorithm>
#include <iomanip>
#include <iostream>
#include <utility>
#include <vector>

using namespace std;

const int maxn = 505;
const double INF = 1e18;

int n, k;
double a[maxn];
double b[maxn];
pair<double, double> p[maxn];
double dp[maxn][maxn];

double f(int s, int cnt) {
    vector<double> v;
    for (int i = s; i < n; i++) {
        v.push_back(a[i]);
    }
    if ((int)v.size() < cnt) return INF;
    sort(v.begin(), v.end());
    double rtn = 0;
    for (int i = 0; i < cnt; i++) {
        rtn += v[i];
    }
    return rtn;
}

double myDP(int x) {
    dp[0][0] = a[0] / (x + 1);
    dp[0][1] = b[0] / 1;
    for (int j = 2; j <= x; j++) dp[0][j] = INF;

    for (int i = 1; i < n; i++) {
        dp[i][0] = dp[i - 1][0] + a[i] / (x + 1);
        for (int j = 1; j <= x; j++) {
            if (j > i + 1) {
                dp[i][j] = INF;
            } else {
                double A = dp[i - 1][j] + a[i] / (x + 1);
                double B = dp[i - 1][j - 1] + b[i] / j;
                dp[i][j] = min(A, B);
            }
        }
    }

    double rtn = INF;
    for (int i = 0; i < n; i++) {
        rtn = min(rtn, dp[i][x] + f(i + 1, k - x) / (x + 1));
    }
    // cout << "solve(" << x << ") = " << rtn << '\n';
    return rtn;
}

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

    cin >> n >> k;
    for (int i = 0; i < n; i++) {
        cin >> a[i] >> b[i];
        if (b[i] == -1) b[i] = INF;
        p[i] = {b[i], a[i]};
    }
    sort(p, p + n);
    for (int i = 0; i < n; i++) {
        b[i] = p[i].first;
        a[i] = p[i].second;
    }
    double an = f(0, k);
    for (int x = 1; x <= k; x++) {
        an = min(an, myDP(x));
    }
    cout << fixed << setprecision(15) << an << '\n';
    return 0;
}

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