Submission #551989

#	Time	Username	Problem	Language	Result	Execution time	Memory
551989		narcissus	Mobile (BOI12_mobile)	C++17	100 / 100	973 ms	35248 KiB

mobile

#include <iostream>
#include <algorithm>
#include <cmath>
#include <iomanip>

using namespace std;

int main()
{
    int n, l;
    cin >> n >> l;
    pair<long long, long long> coords[n];
    for (int i = 0; i < n; i++) {
        cin >> coords[i].first >> coords[i].second;
    }

    double low = 1, high = 2e9;
    while (high - low > 1e-3) {
        double mid = low + (high - low) / 2;
        // cout << mid << ":" << endl;
        double maxv = 0;
        for (int i = 0; i < n; i++) {
            long long x = coords[i].first;
            long long y = coords[i].second;
            double xdist = sqrt(pow(mid, 2) - pow(y, 2));
            double a1 = x - xdist;
            double a2 = x + xdist;
            // cout << "a " << a1 << ' ' << a2 << endl;
            if (a1 <= maxv)
                maxv = max(maxv, a2);
        }
        if (maxv >= l) {
            high = mid;
        } else {
            low = mid;
        }
    }
    cout << fixed << setprecision(4) << low << endl;

    return 0;
}

• Subtask 1: 4 / 4
• Subtask 2: 4 / 4
• Subtask 3: 4 / 4
• Subtask 4: 4 / 4
• Subtask 5: 4 / 4
• Subtask 6: 5 / 5
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• Subtask 15: 5 / 5
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• Subtask 19: 5 / 5
• Subtask 20: 5 / 5
• Subtask 21: 5 / 5