Submission #883339

#	Time	Username	Problem	Language	Result	Execution time	Memory
883339		AkibAzmain	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	492 ms	148076 KiB

shoes

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

long long count_swaps(std::vector<int> a) {
  int n = a.size ();
  map < int, deque < int > > c;
  for (int i = 0; i < n; ++i) c[a[i]].push_back (i);
  vector < int > st (n);
  for (int i = 0; i < n; ++i) st[i] = (i + 1) & -(i + 1);
  auto inc = [&] (int i, int x)
  {
    while (i < n)
      {
        st[i] += x;
        i += (i + 1) & -(i + 1);
      }
  };
  auto sum = [&] (int i)
  {
    int ans = 0;
    while (i >= 0)
      {
        ans += st[i];
        i -= (i + 1) & -(i + 1);
      }
    return ans;
  };
  vector < bool > b (n);
  long long ans = 0;
  for (int i = 0; i < n; ++i)
    {
      if (b[i]) continue;
      int j = c[-a[i]].front ();
      c[-a[i]].pop_front ();
      c[a[i]].pop_front ();
      ans += sum (j) - sum (i) - 1;
      if (a[i] > 0) ++ans;
      inc (i, 1);
      inc (j, -1);
      b[j] = true;
    }
  return ans;
}

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 15 / 15
• Subtask 5: 20 / 20
• Subtask 6: 15 / 15