8B.cc

#include<iostream>
using namespace std;
int nextArrangement(int a[], int n)  //n个皇后
{
    int i;

    for (i = n; i > 1 && a[i] < a[i - 1]; --i);

    if (i == 1) return 0;

    int j;

    for (j = n; a[i - 1] > a[j]; --j);

    int tmp = a[i - 1];
    a[i - 1] = a[j];
    a[j] = tmp;

    for (int p = i, q = n; p < q; ++p, --q) {
        int tmp = a[p];
        a[p] = a[q];
        a[q] = tmp;
    }

    return 1;
}
int isOk(int a[], int n)
{
    for (int i = 1; i < n; ++i)
        for (int j = i + 1; j <= n; ++j)
            if ((j - i) == (a[i] < a[j] ? a[j] - a[i] : a[i] - a[j])) return 0;

    return 1;
}
int main()
{
    int n;

    while (cin >> n) {
        int total = 0;

        if (n < 6 || n > 11) break;

        int a[n + 1];

        for (int i = 1; i <= n; ++i) a[i] = i;

        while (nextArrangement(a, n))
            if (isOk(a, n)) ++total;

        cout << total << endl;
    }

    return 0;
}