algo-homework/3-B-1/main.cpp

#include <iostream>

using namespace std;

int xie[26], nxie[26];
int wei[13], h[13];
int sum;

void dfs(int d, int n)
{
    if (d == n)
    {
        sum++;
        if (sum <= 3)
        {
            for (int i = 0; i < n; i++)
            {
                cout << wei[i]+1 << ' ';
            }
            cout << endl;
        }
    }

    for (int i=0;i<n;i++)
    {
        if (!h[i] && !xie[i+d] && !nxie[n-i-1+d])
        {
            h[i]=xie[i+d]=nxie[n-i-1+d]=1;
            wei[d]=i;
            dfs(d+1,n);
            h[i]=xie[i+d]=nxie[n-i-1+d]=0;
        }
    }
}

int main()
{
    int n;
    cin >> n;
    dfs(0, n);
    cout << sum;
    return 0;
}