Submission #669101

#	Time	Username	Problem	Language	Result	Execution time	Memory
669101		hanlei35	Mobile (BOI12_mobile)	C++17	100 / 100	462 ms	35228 KiB

mobile

#include <iostream>
#include <cmath>
#include <iomanip>
using ll = long long;
using namespace std;

int N, L; 
pair<ll,ll> xy[1000005];
int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cin >> N >> L;
  for(int i=0;i<N;i++){
    cin >> xy[i].first >> xy[i].second;
  }
  double l = 1, r = 1.5E9;
  while(r - l > 1E-4){
    double mid = (l+r)/2, curr = 0;
    for(int i=0;i<N;i++){
      double delta = sqrt(mid*mid - xy[i].second * xy[i].second);
      double a = xy[i].first - delta, b = xy[i].first + delta;
      if(a<=curr) curr = max(curr,b);
    }
    if(curr >= L) r = mid;
    else l = mid;
  }
  cout << fixed << setprecision(4) << l << "\n";
}

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