Submission #1218904

#	Time	Username	Problem	Language	Result	Execution time	Memory
1218904		nhq0914	Mobile (BOI12_mobile)	C++17	100 / 100	391 ms	16092 KiB

mobile

#include <bits/stdc++.h>
#define int long long

const double eps = 1e-5;

int n, L, x[1000000], y[1000000];
double filled, left, right;

signed main() {
	std::ios::sync_with_stdio(0);
	std::cin.tie(0);

	std::cin >> n >> L;
	for(int i = 0; i < n; ++i) std::cin >> x[i] >> y[i];

	std::function <bool(double)> check = [&] (double r) {
		filled = 0;
		for(int i = 0; i < n; ++i) {
			left = x[i] - std::sqrt(r * r - y[i] * y[i]);
			right = x[i] + std::sqrt(r * r - y[i] * y[i]);
			if(left <= filled) filled = std::max(filled, right);
		}
		return filled >= L;
	};

	double l = 0, r = std::sqrt(3e18);
	while(l + eps < r) {
		double mid = (l + r) / 2;
		if(check(mid)) r = mid;
		else l = mid;
	}
	std::cout << std::fixed << std::setprecision(5) << l;
}

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