Submission #1090729

#	Time	Username	Problem	Language	Result	Execution time	Memory
1090729		vjudge1	Safety (NOI18_safety)	C++17	100 / 100	239 ms	21076 KiB

safety

#include <cassert>
#include <iostream>
#include <set>

int main() {
  std::cin.tie(NULL)->sync_with_stdio(false);
  
  int n;
  long long h;
  std::cin >> n >> h;

  int m = 0;
  long long shift = -h, c = 0;
  std::multiset<long long> m_changes[2]; // xpos for each m changes +1
  for (int i = 0; i < n; i++) {
    long long x;
    std::cin >> x;

    // shift by h
    shift += h;
    c -= h * m;

    // append to line
    m_changes[0].insert(x + shift);
    m_changes[1].insert(x - shift);
    
    // normalize
    while (true) {
      long long x_l = *m_changes[0].rbegin();
      long long x_r = *m_changes[1].begin();
      if (x_l - shift <= x_r + shift) {
        break;
      }

      m_changes[0].erase(m_changes[0].find(x_l));
      m_changes[1].erase(m_changes[1].find(x_r));
      x_l -= shift;
      x_r += shift;
      m_changes[0].insert(x_r + shift);
      m_changes[1].insert(x_l - shift);
    }

    // m*x + c + (x - x0) = (m+1)*x + (c - x0)
    m++;
    c -= x;
  }

  while (!m_changes[1].empty()) {
    // pop largest
    long long x = *m_changes[1].rbegin();
    m_changes[1].erase(m_changes[1].find(x));

    // apply shift
    x += shift;
    assert(x >= 0);

    // m*x + c = (m-1)*x + (x + c)
    m--;
    c += x;
  }

  assert(m == 0);
  std::cout << c << std::endl;

  return 0;
}

• Subtask 1: 3 / 3
• Subtask 2: 4 / 4
• Subtask 3: 9 / 9
• Subtask 4: 5 / 5
• Subtask 5: 6 / 6
• Subtask 6: 11 / 11
• Subtask 7: 11 / 11
• Subtask 8: 22 / 22
• Subtask 9: 29 / 29