Submission #1113954

#	Time	Username	Problem	Language	Result	Execution time	Memory
1113954		slycelote	Mobile (BOI12_mobile)	C++17	100 / 100	774 ms	35400 KiB

mobile

#include <cmath>
#include <iostream>
#include <vector>

using namespace std;

int main() {
    cin.tie(0); iostream::sync_with_stdio(false);

    int n;
    double d;
    cin >> n >> d;
    vector<double> x, y;
    x.reserve(n); y.reserve(n);
    while (n--) {
        double xx, yy; cin >> xx >> yy;
        yy = fabs(yy);
        if (!x.empty() && x.back() == xx) {
            y.back() = min(y.back(), yy);
        } else {
            x.push_back(xx);
            y.push_back(yy);
        }
    }
    n = x.size();
    double L = 0, R = 4e9;
    while (R - L > 1e-3) {
        double M = (L + R) / 2;
        vector<pair<double, double>> segs;
        for (int i = 0; i < n; ++i) if (M > y[i]) {
            double len = sqrt(M*M - y[i]*y[i]);
            double start = max((double)0.0, x[i] - len), end = min(d, x[i] + len);
            if (start > end) {
                continue;
            }
            while (!segs.empty() && start < segs.back().second) {
                start = min(start, segs.back().first);
                end = max(end, segs.back().second);
                segs.pop_back();
            }
            segs.push_back({start, end});
        }
        if (segs.empty() || segs.size() > 1 || segs.back().first > 0 || segs.back().second < d) {
            L = M;
        } else {
            R = M;
        }
    }

    cout.precision(20);
    cout << (L+R)/2 << endl;
}

• Subtask 1: 4 / 4
• Subtask 2: 4 / 4
• Subtask 3: 4 / 4
• Subtask 4: 4 / 4
• Subtask 5: 4 / 4
• Subtask 6: 5 / 5
• Subtask 7: 5 / 5
• Subtask 8: 5 / 5
• Subtask 9: 5 / 5
• Subtask 10: 5 / 5
• Subtask 11: 5 / 5
• Subtask 12: 5 / 5
• Subtask 13: 5 / 5
• Subtask 14: 5 / 5
• Subtask 15: 5 / 5
• Subtask 16: 5 / 5
• Subtask 17: 5 / 5
• Subtask 18: 5 / 5
• Subtask 19: 5 / 5
• Subtask 20: 5 / 5
• Subtask 21: 5 / 5