Submission #1126678

#	Time	Username	Problem	Language	Result	Execution time	Memory
1126678		hoaivu	Mobile (BOI12_mobile)	C++20	0 / 100	649 ms	8240 KiB

mobile

#include <bits/stdc++.h>
using namespace std;

const int MAX = 1e6 + 10;
int x[MAX], y[MAX];
int n, l;

bool check(double radius) {
    double now = 0.0;
    for (int i = 0; i < n; ++i) {

        if (radius * radius < 1.0 * y[i] * y[i])
            return false;

        double dx = sqrt(radius * radius - 1.0 * y[i] * y[i]);
        double a = x[i] - dx;
        double b = x[i] + dx;

        if (a > now)
            return false;

        now = max(now, b);
    }

    return now >= l;
}

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

    double low = 0.0, high = 1e9, ans = 1e9;
    for (int i = 0; i < 100; ++i) {
        double mid = (low + high) / 2.0;
        if (check(mid)) {
            ans = mid;
            high = mid;
        } else {
            low = mid;
        }
    }

    cout << fixed << setprecision(6) << ans << "\n";
    return 0;
}

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