Submission #633265

#	Time	Username	Problem	Language	Result	Execution time	Memory
633265		afatpotato	Mobile (BOI12_mobile)	C++14	80 / 100	1087 ms	15956 KiB

mobile

#include <bits/stdc++.h>

using namespace std;



vector<pair<double, double> > tower;
long long n, l;

int main() {
    cin >> n >> l;
    tower.resize(n);
    for (int i = 0; i < n; i++) {
        cin >> tower[i].first >> tower[i].second;
    }

    double low = 0;
    double high = 1.5e9;

    while (high - low > 1e-3) {
        double mid = (low + high) / 2;
        double cur = 0;
        for (int i = 0; i < n; i++) {
            double delta = sqrt(mid * mid - tower[i].second * tower[i].second);
            double a = tower[i].first - delta;
            double b = tower[i].first + delta;
            if (a <= cur) {
                cur = max(cur, b);
            }
        }
        if (cur > l) {
            high = mid;
        } else {
            low = mid;
        }
    }
    cout << fixed;
    cout << setprecision(4);
    cout << low << endl;
}

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