Submission #732496

#	Time	Username	Problem	Language	Result	Execution time	Memory
732496		uy842003	Mobile (BOI12_mobile)	C++17	80 / 100	1095 ms	25088 KiB

mobile

#include <bits/stdc++.h>
using namespace std;
 
const double eps = 1e-4;
 
inline bool cmp_less(const double &a, const double &b) {
    return a + eps < b;
}
 
inline bool cmp_equal(const double &a, const double &b) {
    return abs(a - b) < eps;
}
 
inline bool cmp_less_equal(const double &a, const double &b) {
    return cmp_less(a, b) || cmp_equal(a, b);
}
 
int main() {
 
    int n;
    double len;
    cin >> n >> len;
    vector<pair<double, double>> cor(n);
    for (int i = 0; i < n; i++)
        cin >> cor[i].first >> cor[i].second;
    double l = 0, r = 1e10, m;
    while (cmp_less(l, r)) {
        m = (l + r) / 2;
        double cur_pos = 0;
        for (int i = 0; i < n; i++) {
            if (!cmp_less_equal(m, abs(cor[i].second))) {
                double dx = sqrt(m * m - cor[i].second * cor[i].second);
                if (cmp_less_equal(cor[i].first - dx, cur_pos)) cur_pos = max(cur_pos, cor[i].first + dx);
            }
        }
        if (cmp_less_equal(len, cur_pos))
            r = m;
        else
            l = m + eps;
    }
    cout << setprecision(3) << fixed << r << endl;
 
    return 0;
}

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