Submission #1166171

#	Time	Username	Problem	Language	Result	Execution time	Memory
1166171		fryingduc	Mobile (BOI12_mobile)	C++20	100 / 100	489 ms	16568 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-4;
int n, L;

void solve() {
  cin >> n >> L;
  vector<pair<int, int>> a(n);
  for (auto &i : a) {
    cin >> i.first >> i.second;
  }
  vector<pair<int, int>> nv;
  for (int i = 0; i < n; ++i) {
    int cur = 0;
    long long x = 1e18;
    int t = 1e9;
    while (i + cur < n and a[i].first == a[i + cur].first) {
      if (x > 1ll * a[i + cur].second * a[i + cur].second) {
        x = 1ll * a[i + cur].second * a[i + cur].second;
        t = a[i + cur].second;
      }
      ++cur;
    }
    nv.emplace_back(a[i].first, t);
    i = i + cur - 1;
  }
  a.swap(nv);
  vector<pair<int, int>>().swap(nv);
  n = (int)a.size();
  double le = 0, ri = 1e9;
  double cvg;
  double l, r, len;
  while (ri - le > eps) {
    double mid = (le + ri) / 2;
    cvg = 0;
    for (int i = 0; i < n; ++i) { 
      if (a[i].second > mid) continue;
      len = sqrt(mid * mid - 1ll * a[i].second * a[i].second);
      l = (a[i].first - len);
      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) {
        if (cvg < r) cvg = r;
      }
    }
    if (cvg >= L) {
      ri = mid;
    } else {
      le = mid;
    }
  }
  printf("%8f", ri);
}

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
• Subtask 5: 4 / 4
• Subtask 6: 5 / 5
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• Subtask 19: 5 / 5
• Subtask 20: 5 / 5
• Subtask 21: 5 / 5