Submission #750940

#	Time	Username	Problem	Language	Result	Execution time	Memory
750940		anaduguleanu	Arranging Shoes (IOI19_shoes)	C++14	100 / 100	170 ms	139792 KiB

shoes

#include <iostream>
#include <queue>
#define MAX 200000
using namespace std;
///ifstream cin ("c.in");
///ofstream cout ("c.out");
queue <int> pos[MAX + 10];
int tree[MAX + 10], visited[MAX + 10];
void update(int pos, int val)
{
    for (int i = pos; i <= MAX; i = i + (i & -i))
        tree[i] = tree[i] + val;
}
int query(int pos)
{
    int ans = 0;
    for (int i = pos; i >= 1; i = i - (i & -i))
        ans = ans + tree[i];
    return ans;
}
long long count_swaps(vector <int> v)
{
    for (int i = 1; i <= MAX; i++)
        tree[i] = (i & -i);
    int n = v.size();
    v.insert(v.begin(), 0);
    for (int i = 1; i <= n; i++)
    {
        if (v[i] < 0)
            v[i] = v[i] + n + 1;
        pos[v[i]].push(i);
    }
    long long ans = 0;
    for (int i = 1; i <= n; i++)
        if (visited[i] == 0)
        {
            int current = v[i], next = n - v[i] + 1;
            if (v[i] > n / 2)
                ans--;
            int nextpos = pos[next].front();
            pos[next].pop();
            pos[current].pop();
            ans = ans + query(nextpos) - query(i);
            update(nextpos, -1);
            visited[nextpos] = 1;
            visited[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