Submission #155176

#	Time	Username	Problem	Language	Result	Execution time	Memory
155176		flashmt	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	235 ms	140024 KiB

shoes

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

queue<int> q[200200];
int b[200200], bit[200200];

void add(int x)
{
  for (int i = x; i <= 200000; i += i & -i)
    bit[i]++;
}

int get(int x)
{
  int res = 0;
  for (int i = x; i; i -= i & -i)
    res += bit[i];
  return res;
}

long long count_swaps(vector<int> a)
{
  int n = a.size() / 2, id = 0;
  for (int i = 0; i < n * 2; i++)
    if (q[n - a[i]].empty())
    {
      q[a[i] + n].push(i);
      b[i] = id * 2;
      id++;
    }
    else
    {
      int j = q[n - a[i]].front();
      q[n - a[i]].pop();
      b[i] = b[j] + 1;
      if (a[i] < 0)
        swap(b[i], b[j]);
    }

  long long ans = 0;
  for (int i = 0; i < n * 2; i++)
  {
    ans += i - get(b[i]);
    add(b[i] + 1);
  }
  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