Submission #185318

#	Time	Username	Problem	Language	Result	Execution time	Memory
185318		AlexPop28	Sure Bet (CEOI17_sure)	C++11	100 / 100	133 ms	4596 KiB

sure

#include <bits/stdc++.h>
#define dbg() cerr <<
#define name(x) (#x) << ": " << (x) << ' ' <<

using namespace std;

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);

  int n; cin >> n;
  vector<double> a(n), b(n);
  for (int i = 0; i < n; ++i) {
    cin >> a[i] >> b[i];
    a[i] -= 1.0; b[i] -= 1.0;
  }
  sort(a.rbegin(), a.rend());
  sort(b.rbegin(), b.rend());
  vector<double> sum(n);
  for (int i = 0; i < n; ++i) {
    sum[i] = b[i];
    if (i != 0) sum[i] += sum[i - 1];
  }

  double ans = 0.0, sum_a = 0.0;
  for (int cnt_a = 1; cnt_a <= n; ++cnt_a) {
    auto Compute = [&](int cnt_b) {
      return min(sum_a - cnt_b, sum[cnt_b - 1] - cnt_a);
    };
    sum_a += a[cnt_a - 1];
    int lo = 1, hi = n, res = 0;
    while (lo <= hi) {
      int one = lo + (hi - lo) / 3;
      int two = hi - (hi - lo) / 3;
      if (Compute(one) <= Compute(two)) {
        res = two;
        lo = one + 1;
      } else {
        res = one;
        hi = two - 1;
      }
    }
    // dbg() name(cnt_a) name(res) name(sum_a) name(sum[res - 1]) name(Compute(res)) endl;
    ans = max(ans, Compute(res));
  }
  cout << fixed << setprecision(4) << ans << endl;
}

• Subtask 1: 20 / 20
• Subtask 2: 40 / 40
• Subtask 3: 40 / 40