DFS+模拟 ZOJ 3861 Valid Pattern Lock

题目传送门

 /*
     题意：手机划屏解锁，一笔连通所有数字,输出所有可能的路径；
     DFS：全排列 + ok () 判断函数，去除一些不可能连通的点:)
 */
 #include <cstdio>
 #include <iostream>
 #include <algorithm>
 #include <cstring>
 #include <string>
 #include <map>
 #include <cmath>
 #include <vector>
 #include <set>
 #include <queue>
 using namespace std;

 const int MAXN = ;
 const int INF = 0x3f3f3f3f;
 int a[], ans[];
 int n, x;
 int vis[];
 int res[MAXN][];
 int flag[];

 bool ok(void)
 {
     memset (flag, , sizeof (flag));

     int i;
     for (i=; i<=n-; i++)      //小细节决定成败
     {
         flag[ans[i]] = ;
         if((ans[i] ==  && ans[i+] ==  && flag[] == )|| (ans[i] ==  && ans[i+] ==  && flag[] == ) ||
            (ans[i] ==  && ans[i+] ==  && flag[] == )|| (ans[i] ==  && ans[i+] ==  && flag[] == ) ||
            (ans[i] ==  && ans[i+] ==  && flag[] == )|| (ans[i] ==  && ans[i+] ==  && flag[] == ) ||
            (ans[i] ==  && ans[i+] ==  && flag[] == )|| (ans[i] ==  && ans[i+] ==  && flag[] == ) ||
            (ans[i] ==  && ans[i+] ==  && flag[] == )|| (ans[i] ==  && ans[i+] ==  && flag[] == ) ||
            (ans[i] ==  && ans[i+] ==  && flag[] == )|| (ans[i] ==  && ans[i+] ==  && flag[] == ) ||
            (ans[i] ==  && ans[i+] ==  && flag[] == )|| (ans[i] ==  && ans[i+] ==  && flag[] == ) ||
            (ans[i] ==  && ans[i+] ==  && flag[] == )|| (ans[i] ==  && ans[i+] ==  && flag[] == ) )
            return ;

     }
     if(i == n)
         return true;
 }

 void DFS(int cnt)
 {
     if (cnt == n + )
     {
         if (ok ())
         {
             x++;
             for (int i=; i<=n; i++)
             {
                 res[x][i] = ans[i];
             }
         }

         return ;
     }

     for (int i=; i<=n; i++)
     {
         if (!vis[a[i]])
         {
             ans[cnt] = a[i];
             vis[a[i]] = ;
             DFS (cnt + );
             vis[a[i]] = ;
         }
     }
 }

 int main(void)        //ZOJ 3861 Valid Pattern Lock
 {
     //freopen ("B.in", "r", stdin);

     int t;
     scanf ("%d", &t);
     while (t--)
     {
         //memset (res, -1, sizeof (res));     //这句话没写导致WA n次！！！
         memset (vis, , sizeof (vis));            //注意初始化，上面的作用已在ok () Debug 出来了
         scanf ("%d", &n);

         for (int i=; i<=n; ++i)    scanf ("%d", &a[i]);
         sort(a+,a+n+);
         x = ;
         DFS ();

         printf ("%d\n", x);
         for (int i=; i<=x; ++i)
         {
             for (int j=; j<=n; ++j)
             {
                 printf ("%d%c", res[i][j], (j==n) ? '\n' : ' ');
             }
         }

     }

     return ;
 }