Submission #521933

#	Time	Username	Problem	Language	Result	Execution time	Memory
521933		sofapuden	Mobile (BOI12_mobile)	C++14	52 / 100	791 ms	35292 KiB

mobile

#pragma GCC optimize("Ofast")
#include<bits/stdc++.h>
 
using namespace std;
 
int main(){
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	double k;
	int n; cin >> n >> k;
	vector<pair<double,double>> v(n);
	for(auto &x : v)cin >> x.first >> x.second;
	double l = 0, r = 2e9;
	while((r-l) > 0.001){
		double mid = (l+r)/2.0;
		vector<double> ran1, ran2;
		for(int i = 0; i < n; ++i){
			if(abs(v[i].second) >= mid)continue;
			double z = sqrt(mid*mid-v[i].second*v[i].second);
			while(ran1.size() && max(v[i].first-z,0.0) < ran1.back()){
				ran1.pop_back();
				ran2.pop_back();
			}
			if(ran1.empty() || v[i].first+z > ran2.back()){
				if(ran1.size() && v[i].first-z < ran2.back()){
					ran1.back() = max(0.0,min(v[i].first-z,ran1.back()));
					ran2.back() = min(v[i].first+z,k);
				}
				else{
					ran1.push_back(max(min(v[i].first-z,k),0.0));
					ran2.push_back(min(max(v[i].first+z,0.0),k));
				}
			}
			if(ran1.back() == ran2.back()){
				ran1.pop_back();
				ran2.pop_back();
			}
		}
		if(ran1.empty() || ran1[0] != 0 || ran2.back() != k){
			l = mid;
			continue;
		}
		bool ok = 1;
		for(int i = 1; i < (int)ran1.size(); ++i){
			if(ran2[i-1] < ran1[i]){
				ok = 0;
				break;
			}
			if(ran2[i] == k)break;
		}
		if(ok){
			r = mid;
		}
		else{
			l = mid;
		}
	}
	printf("%.3f\n", l);
 
}

• Subtask 1: 4 / 4
• Subtask 2: 0 / 4
• Subtask 3: 4 / 4
• Subtask 4: 4 / 4
• Subtask 5: 0 / 4
• Subtask 6: 5 / 5
• Subtask 7: 5 / 5
• Subtask 8: 0 / 5
• Subtask 9: 5 / 5
• Subtask 10: 0 / 5
• Subtask 11: 0 / 5
• Subtask 12: 0 / 5
• Subtask 13: 5 / 5
• Subtask 14: 5 / 5
• Subtask 15: 5 / 5
• Subtask 16: 0 / 5
• Subtask 17: 0 / 5
• Subtask 18: 0 / 5
• Subtask 19: 5 / 5
• Subtask 20: 0 / 5
• Subtask 21: 5 / 5