Submission #1057220

#	Time	Username	Problem	Language	Result	Execution time	Memory
1057220		juicy	Seesaw (JOI22_seesaw)	C++17	100 / 100	55 ms	15568 KiB

seesaw

#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif

const int N = 2e5 + 5;

int n;
int a[N], fre[N];
long long pf[N];

double qry(int l, int r) {
  return (double) (pf[r] - pf[l - 1]) / (r - l + 1);
}

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

  cin >> n;
  for (int i = 1; i <= n; ++i) {
    cin >> a[i];
    pf[i] = pf[i - 1] + a[i];
  }
  double A = qry(1, n);
  vector<pair<double, int>> cands = {{A, n}};
  for (int l = 1; l < n; ++l) {
    int L = 1, R = n - l + 1, p = 0;
    while (L <= R) {
      int md = (L + R) / 2; 
      if (qry(md, md + l - 1) < A) {
        p = md;
        L = md + 1;
      } else {
        R = md - 1;
      }
    }
    cands.push_back({qry(p, p + l - 1), l});
    cands.push_back({qry(p + 1, p + l), l});
  }
  sort(cands.begin(), cands.end());
  double res = 1e9;
  for (int i = 0, j = 0, cnt = 0; i < cands.size(); ++i) {
    while (j < cands.size() && cnt < n) {
      cnt += !fre[cands[j++].second]++;
    }
    if (cnt == n) {
      res = min(res, cands[j - 1].first - cands[i].first);
    }
    cnt -= !--fre[cands[i].second];
  }
  cout << fixed << setprecision(12) << res;
  return 0;
}

Compilation message (stderr)

seesaw.cpp: In function 'int main()':
seesaw.cpp:47:37: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<double, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   47 |   for (int i = 0, j = 0, cnt = 0; i < cands.size(); ++i) {
      |                                   ~~^~~~~~~~~~~~~~
seesaw.cpp:48:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<double, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   48 |     while (j < cands.size() && cnt < n) {
      |            ~~^~~~~~~~~~~~~~

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