제출 #990610

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
990610		Ska	Mobile (BOI12_mobile)	C++14	100 / 100	388 ms	35176 KiB

mobile

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

const int N = 1e6 + 5;

int n;
double m;
double x[N], y[N];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> n >> m;
    double l = 2e9, r = 1.5e9;
    for (int i = 1; i <= n; ++i) {
        cin >> x[i] >> y[i];
        l = min(l, abs(y[i]));
    }
    while (r - l >= 1e-3) {
        double mid = (l + r) / 2;
        double cur = 0;
        for (int i = 1; i <= n; ++i) {
            if (mid < abs(y[i])) {
                continue;
            }
            double d = sqrt(mid * mid - y[i] * y[i]);
            double a = x[i] - d, b = x[i] + d;
            if (a <= cur) {
                cur = max(cur, b);
            }
            if (cur >= m) {
                break;
            }
        }
        if (cur >= m) {
            r = mid;
        } else {
            l = mid;
        }
    }
    cout << fixed << setprecision(6) << l << '\n';
}

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