搜索可以解决

#include <bits/stdc++.h>

#define endl "\n"
#define debug freopen("in.txt", "r", stdin), freopen("out.txt", "w", stdout)
using namespace std;

int n, a[7][7], cnt, ans[7];

void dfs(int x)
{
    if (x == 1)
    {
        ans[x] = 1;
        dfs(x + 1);
        return;
    }
    if (x == n + 1)
    {
        cnt++;
        for (int i = 1; i <= n; i++)
            printf("%d ", ans[i]);
        printf("\n");
        return;
    }
    for (int i = 1; i <= 4; i++)
    {
            bool flag = true;
            for (int j = 1; j <= n; j++)
            {
                if (a[x][j] && i == ans[j])
                {
                    flag = false;
                    break;
                }
            }
            if (flag)
            {
                ans[x] = i;
                dfs(x + 1);
                ans[x] = 0;
            }
    }
}

int main()
{
    // freopen("in.txt", "r", stdin);
    scanf("%d", &n);
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= n; j++)
            scanf("%d", &a[i][j]);

    dfs(1); // 递归搜索
    cout << cnt << endl;
    return 0;
}