USACO 5.2 Wisconsin Squares(DFS)

好扯淡。。。

  1 /*
  2  ID: cuizhe
  3  LANG: C++
  4  TASK: wissqu
  5 */
  6 #include <iostream>
  7 #include <cstdio>
  8 #include <cstring>
  9 #include <queue>
 10 #include <map>
 11 #include <ctime>
 12 #include <cmath>
 13 #include <algorithm>
 14 using namespace std;
 15 char str[10][10];
 16 int flag[10][10],o[6];
 17 int q1[20],q2[20],q3[20];
 18 int a[9] = {0,0,0,1,1,1,-1,-1,-1};
 19 int b[9] = {1,-1,0,0,1,-1,0,1,-1};
 20 int num = 0;
 21 int judge(int x,int y,char ch)
 22 {
 23     int i;
 24     for(i = 0; i < 9; i ++)
 25     {
 26         if(x+a[i] >= 0&&x+a[i] < 4&&y+b[i] >= 0&&y+b[i] < 4)
 27         {
 28             if(ch == str[x+a[i]][y+b[i]])
 29                 return 0;
 30         }
 31     }
 32     return 1;
 33 }
 34 void dfs(int step)
 35 {
 36     int i,j,k,top,u;
 37     char temp;
 38     int quer[21],quec[21];
 39     if(step > 16)
 40     {
 41         num ++;
 42         if(num == 1)
 43         {
 44             for(i = 1; i <= 16; i ++)
 45             {
 46                 printf("%c %d %d\n",q1[i]+'A',q2[i]+1,q3[i]+1);
 47             }
 48         }
 49         return ;
 50     }
 51     top = 1;
 52     for(j = 0; j < 4; j ++)
 53     {
 54         for(k = 0; k < 4; k ++)
 55         {
 56             if(!flag[j][k])
 57             {
 58                 quer[top] = j;
 59                 quec[top] = k;
 60                 top ++;
 61             }
 62         }
 63     }
 64     for(i = 0; i < 5; i ++)
 65     {
 66         if(o[i])
 67         {
 68             for(u = 1; u < top; u ++)
 69             {
 70                 j = quer[u];
 71                 k = quec[u];
 72                 if(judge(j,k,i+'A')&&!flag[j][k])
 73                 {
 74                     flag[j][k] = 1;
 75                     o[i] --;
 76                     temp = str[j][k];
 77                     str[j][k] = i + 'A';
 78                     q1[step] = i;
 79                     q2[step] = j;
 80                     q3[step] = k;
 81                     dfs(step+1);
 82                     o[i] ++;
 83                     flag[j][k] = 0;
 84                     str[j][k] = temp;
 85                 }
 86             }
 87         }
 88     }
 89     return ;
 90 }
 91 int main()
 92 {
 93     int i,j;
 94     char temp;
 95     for(i = 0; i < 4; i ++)
 96         scanf("%s",str[i]);
 97     for(i = 0; i < 5; i ++)
 98         o[i] = 3;
 99     for(i = 0; i < 4; i ++)
100     {
101         for(j = 0; j < 4; j ++)
102         {
103             if(judge(i,j,'D'))
104             {
105                 q1[1] = 3;
106                 q2[1] = i;
107                 q3[1] = j;
108                 temp = str[i][j];
109                 str[i][j] = 'D';
110                 dfs(2);
111                 str[i][j] = temp;
112             }
113         }
114     }
115     printf("%d\n",num);
116     return 0;
117 }

 

posted @ 2013-05-23 09:47  Naix_x  阅读(198)  评论(0)  编辑  收藏  举报