Submission #1006061

#	Time	Username	Problem	Language	Result	Execution time	Memory
1006061		tch1cherin	Seesaw (JOI22_seesaw)	C++17	100 / 100	152 ms	10704 KiB

seesaw

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

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  cout << fixed << setprecision(12);
  int N;
  cin >> N;
  vector<int> A(N);
  for (int &value : A) {
    cin >> value;
  }
  vector<long long> pref(N + 1);
  for (int i = 0; i < N; i++) {
    pref[i + 1] = pref[i] + A[i];
  }
  auto Mean = [&](int L, int R) { return 1.L * (pref[R] - pref[L]) / (R - L); };
  vector<array<int, 2>> seg = {{0, N}};
  for (int len = 1; len < N; len++) {
    int low = -1, high = N - len + 1;
    while (high - low > 1) {
      int mid = (low + high) / 2;
      if (Mean(mid, mid + len) <= Mean(0, N)) {
        low = mid;
      } else {
        high = mid;
      }
    }
    if (low >= 0) {
      seg.push_back({low, low + len});
    }
    if (high + len <= N) {
      seg.push_back({high, high + len});
    }
  }
  sort(seg.begin(), seg.end(), [&](array<int, 2> x, array<int, 2> y) {
    return Mean(x[0], x[1]) < Mean(y[0], y[1]);
  });
  vector<int> cnt(N + 1);
  int bad_count = N;
  long double result = numeric_limits<long double>::max();
  for (int i = 0, j = 0; i < int(seg.size()); i++) {
    while (j < int(seg.size()) && bad_count > 0) {
      bad_count -= cnt[seg[j][1] - seg[j][0]]++ == 0;
      j++;
    }
    if (bad_count == 0) {
      result = min(result, Mean(seg[j - 1][0], seg[j - 1][1]) - Mean(seg[i][0], seg[i][1]));
    }
    bad_count += --cnt[seg[i][1] - seg[i][0]] == 0;
  }
  cout << result << "\n";
}

• Subtask 1: 1 / 1
• Subtask 2: 33 / 33
• Subtask 3: 33 / 33
• Subtask 4: 33 / 33