Submission #857564

#	Time	Username	Problem	Language	Result	Execution time	Memory
857564		sleepntsheep	Arranging Shoes (IOI19_shoes)	C++17	10 / 100	1 ms	2484 KiB

shoes

#include <vector>
#include <cstdint>
#include <iostream>
#include <algorithm>

#define N 200005

int fw[N], posraw[N<<1];
int *pos = posraw+N;

void upd(int p, int k) { for (++p; p < N; p+=p&-p) fw[p] += k; }
int qry(int p) { if(p<0)return 0;int z = 0; for (++p; p; p-=p&-p) z += fw[p]; return z; }

int64_t count_swaps(std::vector<int> v)
{
    int64_t z = 0;
    int n = v.size() >> 1, f = 0;

    for (int i = 0; i < (int)v.size(); ++i) pos[v[i]] = i;
    for (int i = 0; i < 2 * n; ++i, ++f)
    {
        if (qry(i) - qry(i-1) == 1) continue;
        int corresponding = pos[-v[i]] + (qry(2*n) - qry(pos[-v[i]]));
        z += corresponding - i*2 - 1 + (v[i] > 0);
        upd(pos[-v[i]], 1);
    }

    return z;
}

#if 0
int main()
{
    std::cout << count_swaps({2, 1, -1, -2});
}
#endif

• Subtask 1: 10 / 10
• Subtask 2: 0 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 15