제출 #906139

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
906139		Nonoze	Mobile (BOI12_mobile)	C++17	25 / 100	240 ms	21044 KiB

mobile

#include <bits/stdc++.h>

#define int long long
#define sz(x) (int)(x.size())

using namespace std;

int n, L;
vector<pair<double, double>> a;

double dist(double x1, pair<double, double> other) {
	double y1=0;
	double x2=other.first, y2=other.second;
	return ((double)sqrt((double)((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1))));
}

void solve() {
	cin >> n >> L;
	a.clear();
	for (int i=0; i<n; i++) {
		int x, y; cin >> x >> y;
		if (!a.empty() && x==a.back().first) {
			if (abs(y)<abs(a.back().second)) a.back().second=y;
			continue;
		}
		a.push_back({x, y});
	}
	double l=0, r=1e9;
	while (r-l>=0.0001) {
		double mid=(l+r)/2;
		double borne=0;
		for (int i=0; i<n; i++) {
			double x=a[i].first, y=a[i].second;
			double dist=sqrt((double)(mid*mid-y*y));
			if (x-dist<=borne && x+dist>borne) borne=x+dist;
		}
		if (borne>=L) r=mid;
		else l=mid;
	}
	cout << fixed << setprecision(3) << l << endl;
	return;
}


signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	solve();
	return 0;
}

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