poj3009

  1 #include <iostream>
  2
  3 using namespace std;
  4
  5 int w, h;
  6 int MAP[41][41];
  7 int sx, sy, ex, ey;
  8 int res;
  9 int dx[4] = {
 10     1, -1, 0, 0
 11 };
 12 int dy[4] = {
 13     0, 0, 1, -1
 14 };
 15
 16 int runing(int &x, int &y, int dir)
 17 {
 18     for(;;)
 19     {
 20         int nx = x + dx[dir];
 21         int ny = y + dy[dir];
 22         if(nx >= 0 && nx < w && ny >= 0 && ny < h)
 23         {
 24             if(MAP[ny][nx] == 1)
 25             {
 26                 return 1;
 27             }
 28             else if(nx == ex && ny == ey)
 29             {
 30                 return 0;
 31             }
 32         }
 33         else
 34         {
 35             return -1;
 36         }
 37         x = nx;
 38         y = ny;
 39     }
 40 }
 41
 42 void dfs(int x, int y, int sum)
 43 {
 44     int nx, ny;
 45     //´óÓÚ10£¬¼ôÖ¦
 46     if(sum > 10)
 47         return ;
 48
 49
 50     //Ëĸö·½Ïò½øÐÐËÑÑ°
 51     for(int i = 0; i < 4; ++i)
 52     {
 53         nx = x + dx[i];
 54         ny = y + dy[i];
 55         if(nx >= 0 && nx < w && ny >= 0 && ny < h)
 56         {
 57             if(MAP[ny][nx] == 1)
 58             {
 59                 continue;
 60             }
 61         }
 62         else
 63             continue;
 64         nx = x; ny = y;
 65         int temp = runing(nx, ny, i);
 66         //ÍùÕâ¸ö·½ÏòÅöµ½µÄÊÇǽ
 67         if(temp == 1)
 68         {
 69             MAP[ny+dy[i]][nx+dx[i]] = 0;
 70             dfs(nx, ny, sum+1);
 71             MAP[ny+dy[i]][nx+dx[i]] = 1;
 72
 73         }
 74         //ÍùÕâ¸ö·½Ïò³ö½çÁË
 75         else if(temp == -1)
 76         {
 77             continue;
 78         }
 79         //ÍùÕâ¸ö·½Ïòµ½´ïÁËÖÕµã
 80         else if(temp == 0)
 81         {
 82              if(res > sum)
 83                  res = sum;
 84         }
 85     }
 86
 87 }
 88
 89 void solver()
 90 {
 91     res = 11;
 92     dfs(sx, sy, 1);
 93
 94 }
 95 int main()
 96 {
 97     while(cin >> w >> h)
 98     {
 99         if(w == 0 && h == 0)
100             break;
101         //input
102         for(int i = 0; i < h; ++i)
103         {
104             for(int j = 0; j < w; ++j)
105             {
106                 cin >> MAP[i][j];
107                 if(MAP[i][j] == 2)
108                 {
109                     sx = j;
110                     sy = i;
111                 }
112                 if(MAP[i][j] == 3)
113                 {
114                     ex = j;
115                     ey = i;
116                 }
117             }
118         }
119         //solver
120         solver();
121         //output
122         if(res > 10)
123             cout << -1 << endl;
124         else
125             cout << res << endl;
126     }
127
128     return 0;
129 }