Submission #998937

#	Time	Username	Problem	Language	Result	Execution time	Memory
998937		hippo123	Mobile (BOI12_mobile)	C++17	12 / 100	541 ms	23632 KiB

mobile

#include <bits/stdc++.h>
using namespace std;
 
#define pr pair<int, int>
#define ll long long
#define pb push_back
#define f first
#define s second
vector<pr> d(1000001);
int n; double L;

bool comp(pr a, pr b){
	if(a.f==b.f) return a.s*a.s<b.s*b.s;
	return a.f<b.f;
}


int main(){
	 cin>>n>>L;
	

	for (int i=0; i<n; i++) {
		cin>>d[i].f>>d[i].s; 
	}
	
	//sort(d.begin(), d.begin()+n, comp);
	
	//for (int i=0; i<n; i++) cout<<d[i].f<<" " <<d[i].s<<" :"<<endl;
	
	double lft=0; double rht=L;
	while (rht-lft>1e-5){
		double mid=lft+(rht-lft)/2;
		//cout<<" lft/rht/mid= "<<lft<<" "<<rht<<" "<<mid<<endl;

		double curr=0;
		for (int i=0; i<n; i++){
			double dx=sqrt(mid*mid-d[i].s*d[i].s);
			double x1, x2;
			x1=d[i].f-dx; x2=d[i].f+dx;
			if(x1<=curr) curr=max(curr, x2); 
		}
		if(curr>=L) rht=mid;
		else lft=mid;
	
	}
	cout << fixed <<setprecision(4);
	cout<<lft<<endl;
	
}

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