Submission #1066375

#	Time	Username	Problem	Language	Result	Execution time	Memory
1066375		JohnnyVenturas	Mobile (BOI12_mobile)	C++17	100 / 100	839 ms	15976 KiB

mobile

#include <bits/stdc++.h>

using namespace std;

const int MAXN = 1e6;

struct point {
    long long x, y;
};

point receivers[MAXN];

double first_true(double low, double high, function<bool(double)> f) {
    --low, ++high;
    double mid;
    while (high - low > 1e-3) {
        mid = low + (high - low) /2;
        if (f(mid)) {
            high = mid;
        } else {
            low = mid;
        }
    }

    return high;
}

int main() {
    int n, l;
    cin >> n >> l;

    for (int i = 0; i < n; ++i) {
        cin >> receivers[i].x >> receivers[i].y;
    }

    cout << fixed << setprecision(4) << first_true(0, 2e9, [&](double r) {
        double high = 0;

        for (int i = 0; i < n; ++i) {
            double left = receivers[i].x -
                           sqrt(r * r - receivers[i].y * receivers[i].y);
            double right =  receivers[i].x +
                           sqrt(r * r - receivers[i].y * receivers[i].y);

            if (left <= high) {
                high = max(high, right);
            }
        }

        return high >= l;
    });
}

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