Submission #1167895

#	Time	Username	Problem	Language	Result	Execution time	Memory
1167895		julia_08	Mobile (BOI12_mobile)	C++20	100 / 100	488 ms	16096 KiB

mobile

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

using ld = long double;
using ll = long long;

const int MAXN = 1e6 + 10;

ll x[MAXN], y[MAXN];

int n; ll L;

bool check(ld d){

  ld max_x = 0;

  for(int i=1; i<=n; i++){

    ld delta = (ld) (d * d - y[i] * y[i]);

    if(delta < 1e-9) continue;

    ld l = (ld) (x[i] - sqrt(delta)), r = (ld) (x[i] + sqrt(delta));

    if(l <= max_x) max_x = max(max_x, r);

  }

  return max_x < L;
}

ld bs(){

  ld l = 0, r = 1e10;

  for(int i=0; i<75; i++){
    ld m = (l + r) / 2;
    if(check(m)) l = m;
    else r = m;
  }

  return l;
}

int main(){
  cin.tie(0)->sync_with_stdio(0);

  cin >> n >> L;

  for(int i=1; i<=n; i++){
    cin >> x[i] >> y[i];
  }

  cout << fixed << setprecision(6) << bs() << "\n";

  return 0;
}

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