【HDOJ】2553 N皇后问题

超级经典神搜，这题以前做过，知道需要打表。没优化。

#include <stdio.h>
#include <string.h>

#define MAXNUM 12
/*
int queens[MAXNUM][MAXNUM];
int count;
int dir[4][2] = {{-1,-1},{-1,1},{1,1},{1,-1}};

void dfs(int c, int n) {
    int i, j, tmp;
    int x, y, dx, dy;

    for (i=1; i<=n; ++i) {
        tmp = 1;
        for (j=0; j<4; ++j) {
            dx = dir[j][0];
            dy = dir[j][1];
            x = c + dx;
            y = i + dy;
            while (x>=1 && x<=n && y>=1 && y<=n) {
                if (queens[x][y]) {
                    tmp = 0;
                    break;
                }
                x += dx;
                y += dy;
            }
            if (tmp == 0)
                break;
        }
        for (j=1; j<=n; ++j)
            if (queens[j][i]) {
                tmp = 0;
                break;
            }

        if (tmp) {
            if (c == n) {
                count++;
                return ;
            }
            queens[c][i] = 1;
            dfs(c+1, n);
            queens[c][i] = 0;
        }
    }
}

int main() {
    int n;

    while (scanf("%d", &n)!=EOF && n) {
        memset(queens, 0, sizeof(queens));
        count = 0;
        dfs(1, n);
        printf("%d\n", count);
    }

    return 0;
}
*/

int kinds[] = {0, 1, 0, 0, 2, 10, 4, 40, 92, 352, 724};

int main() {
    int n;

    while (scanf("%d", &n)!=EOF && n) {
        printf("%d\n", kinds[n]);
    }

    return 0;
}