Submission #1166157

#	Time	Username	Problem	Language	Result	Execution time	Memory
1166157		fryingduc	Mobile (BOI12_mobile)	C++20	50 / 100	1096 ms	8264 KiB

mobile

#include "bits/stdc++.h"

using namespace std;

#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif

const int maxn = 1e6 + 6;
const double eps = 1e-7;
int n, L;
pair<int, int> a[maxn];

bool check(double mid) {
  double cvg = 0;
  for (int i = 1; i <= n; ++i) { 
    if (a[i].second > mid) continue;
    auto calc = [&](double a, double c) {
      return sqrtl(c * c - a * a);
    };
    double len = calc(a[i].second, mid);
    double l = (a[i].first - len);
    double r = (a[i].first + len);
    if (l > L || r < 0) continue;
    l = max(l, 0.0);
    r = min(r, L * 1.0);
    if (cvg >= l) {
      cvg = max(cvg, r);
    }
  }
  return cvg >= L;
}

void solve() {
  cin >> n >> L;
  for (int i = 1; i <= n; ++i) {
    cin >> a[i].first >> a[i].second;
  }
  double l = 0, r = 1e9;
  for (int ite = 0; ite < 80; ++ite) {
    if (r - l > eps) {
      double mid = (l + r) / 2;
      if (check(mid)) {
        r = mid;
      } else {
        l = mid;
      }
    }
  }
  
  cout << fixed << setprecision(12) << r;
}

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

• Subtask 1: 4 / 4
• Subtask 2: 4 / 4
• Subtask 3: 4 / 4
• Subtask 4: 4 / 4
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• Subtask 10: 5 / 5
• Subtask 11: 5 / 5
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