Submission #475572

#	Time	Username	Problem	Language	Result	Execution time	Memory
475572		flashmt	Tortoise (CEOI21_tortoise)	C++17	48 / 100	3085 ms	143712 KiB

tortoise

#include <bits/stdc++.h>
using namespace std;
const int oo = 1 << 30;

int main()
{
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < n; i++)
    cin >> a[i];

  vector<int> l(n), r(n);
  for (int i = 0, last = -oo; i < n; i++)
    if (a[i] < 0) last = i;
    else l[i] = last;
  for (int i = n - 1, last = oo; i >= 0; i--)
    if (a[i] < 0) last = i;
    else r[i] = last;

  if (n > 5000)
    return 0;

  int mx = (n * 3 + 1) / 2;
  vector<vector<int>> f(n, vector<int>(mx + 1, oo));
  for (int i = 0; i < n; i++)
    if (a[i] > 0)
    {
      f[i][0] = i;
      for (int ii = 0; ii < i; ii++)
        if (a[ii] > 0)
          for (int j = 0; j <= mx; j++)
            if (f[ii][j] <= ii * 2)
            {
              f[i][j] = min(f[i][j], f[ii][j] + i - ii);
              if (j < mx)
              {
                if (r[ii] < n)
                  f[i][j + 1] = min(f[i][j + 1], f[ii][j] + r[ii] - ii + abs(i - r[ii]));
                if (l[ii] >= 0)
                  f[i][j + 1] = min(f[i][j + 1], f[ii][j] + ii + i - 2 * l[ii]);
              }
            }

      int d = min(r[i] - i, i - l[i]);
      for (int j = mx - 1; j >= 0; j--)
      {
        int cur = f[i][j];
        for (int jj = 1; jj < a[i]; jj++)
        {
          cur += d * 2;
          if (cur > i * 2)
            break;
          f[i][j + jj] = min(f[i][j + jj], cur);
        }
      }
    }

  int ans = 0, total = 0;
  for (int i = 0; i < n; i++)
  {
    for (int j = 0; j <= mx; j++)
      if (f[i][j] <= i * 2)
        ans = max(ans, j + 1);
    if (a[i] > 0)
      total += a[i];
  }

  cout << total - ans << endl;
}

• Subtask 1: 8 / 8
• Subtask 2: 10 / 10
• Subtask 3: 30 / 30
• Subtask 4: 0 / 25
• Subtask 5: 0 / 27