Submission #974143

#	Time	Username	Problem	Language	Result	Execution time	Memory
974143		AksLolCoding	Mobile (BOI12_mobile)	C++17	90 / 100	1083 ms	49128 KiB

mobile

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

using ld = long double;
using ld2 = array<ld, 2>;

const ld diff = 1e-5;
int n;
ld h;
vector<ld2> pts;

ld2 range(ld dist, ld2& pt) {
	ld dx = sqrt(dist*dist - pt[1]*pt[1]);
	return {pt[0] - dx, pt[0] + dx};
}

bool check(ld dist) {
	ld left = 0;
	for (ld2& pt: pts) {
		ld2 r = range(dist, pt);
		if (r[0] <= left) left = max(left, r[1]);
	}
	return (left >= h);
}

int main() {
	cin.tie(0)->sync_with_stdio(0);
	cin >> n >> h;
	pts.resize(n);
	for (auto& i: pts) cin >> i[0] >> i[1];

	// solve
	ld l = 0, r = 2e9, m;
	while (r - l > diff) {
		m = (r + l) / 2;
		if (check(m)) r = m;
		else l = m;
	}
	printf("%.5Lf\n", m);
}

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