DFS+模拟 ZOJ 3861 Valid Pattern Lock

  1 /*
  2     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；
  3     DFS：全排列 + ok () 判断函数，去除一些不可能连通的点:)
  4 */
  5 #include <cstdio>
  6 #include <iostream>
  7 #include <algorithm>
  8 #include <cstring>
  9 #include <string>
 10 #include <map>
 11 #include <cmath>
 12 #include <vector>
 13 #include <set>
 14 #include <queue>
 15 using namespace std;
 16 
 17 const int MAXN = 500000;
 18 const int INF = 0x3f3f3f3f;
 19 int a[11], ans[11];
 20 int n, x;
 21 int vis[11];
 22 int res[MAXN][11];
 23 int flag[10];
 24 
 25 bool ok(void)
 26 {
 27     memset (flag, 0, sizeof (flag));
 28 
 29     int i;
 30     for (i=1; i<=n-1; i++)      //小细节决定成败
 31     {
 32         flag[ans[i]] = 1;
 33         if((ans[i] == 1 && ans[i+1] == 9 && flag[5] == 0)|| (ans[i] == 9 && ans[i+1] == 1 && flag[5] == 0) ||
 34            (ans[i] == 1 && ans[i+1] == 3 && flag[2] == 0)|| (ans[i] == 3 && ans[i+1] == 1 && flag[2] == 0) ||
 35            (ans[i] == 1 && ans[i+1] == 7 && flag[4] == 0)|| (ans[i] == 7 && ans[i+1] == 1 && flag[4] == 0) ||
 36            (ans[i] == 2 && ans[i+1] == 8 && flag[5] == 0)|| (ans[i] == 8 && ans[i+1] == 2 && flag[5] == 0) ||
 37            (ans[i] == 4 && ans[i+1] == 6 && flag[5] == 0)|| (ans[i] == 6 && ans[i+1] == 4 && flag[5] == 0) ||
 38            (ans[i] == 3 && ans[i+1] == 9 && flag[6] == 0)|| (ans[i] == 9 && ans[i+1] == 3 && flag[6] == 0) ||
 39            (ans[i] == 7 && ans[i+1] == 9 && flag[8] == 0)|| (ans[i] == 9 && ans[i+1] == 7 && flag[8] == 0) ||
 40            (ans[i] == 3 && ans[i+1] == 7 && flag[5] == 0)|| (ans[i] == 7 && ans[i+1] == 3 && flag[5] == 0) )
 41            return 0;
 42 
 43     }
 44     if(i == n)
 45         return true;
 46 }
 47 
 48 void DFS(int cnt)
 49 {
 50     if (cnt == n + 1)
 51     {
 52         if (ok ())
 53         {
 54             x++;
 55             for (int i=1; i<=n; i++)
 56             {
 57                 res[x][i] = ans[i];
 58             }
 59         }
 60 
 61         return ;
 62     }
 63 
 64     for (int i=1; i<=n; i++)
 65     {
 66         if (!vis[a[i]])
 67         {
 68             ans[cnt] = a[i];
 69             vis[a[i]] = 1;
 70             DFS (cnt + 1);
 71             vis[a[i]] = 0;
 72         }
 73     }
 74 }
 75 
 76 int main(void)        //ZOJ 3861 Valid Pattern Lock
 77 {
 78     //freopen ("B.in", "r", stdin);
 79 
 80     int t;
 81     scanf ("%d", &t);
 82     while (t--)
 83     {
 84         //memset (res, -1, sizeof (res));     //这句话没写导致WA n次！！！
 85         memset (vis, 0, sizeof (vis));            //注意初始化，上面的作用已在ok () Debug 出来了
 86         scanf ("%d", &n);
 87 
 88         for (int i=1; i<=n; ++i)    scanf ("%d", &a[i]);
 89         sort(a+1,a+n+1);
 90         x = 0;
 91         DFS (1);
 92 
 93         printf ("%d\n", x);
 94         for (int i=1; i<=x; ++i)
 95         {
 96             for (int j=1; j<=n; ++j)
 97             {
 98                 printf ("%d%c", res[i][j], (j==n) ? ‘\n‘ : ‘ ‘);
 99             }
100         }
101 
102     }
103 
104     return 0;
105 }