determinanta

#include <fstream>
#define zorro(x) ( (x ^ (x - 1)) & x )
using namespace std;
ifstream f("determinanta.in");
ofstream g("determinanta.out");
int n, i, j, ok, l, c;
long long inv;
int AIB[100003], lin[100003], col[100003], p[100003];

void Add(int x, int quantity)
{
    int i;

    for (i = x; i <= n; i += zorro(i))
        AIB[i] += quantity;
}

int Compute(int x)
{
    int i, ret = 0;

    for (i = x; i > 0; i -= zorro(i))
        ret += AIB[i];
    return ret;
}

int main()
{
    f >> n;
    ok = 1;
    for(i = 1; i <= n; i++)
    {
        f >> l >> c;
        if(lin[l] == 1) ok = 0;
        if(col[c] == 1) ok = 0;
        lin[l] = 1;
        col[c] = 1;
        p[l] = c;
    }
    if(ok == 1)
    {
        inv = 0;
        for(j = 1; j <= n; j++)
        {
            inv += Compute(n)-Compute(p[j]);
            Add(p[j],1);
        }
        if(inv % 2 == 1) g << -1;
        else g << 1;
    }
    else
    {
        g << 0;
    }
}