[dfs] [FloodFill] POJ1979 Red And Black

 1 #include <iostream>
 2 #include <string.h>
 3 using namespace std;
 4 
 5 bool map[22][22];
 6 bool visit[22][22];
 7 int answer;
 8 int W, H;                              // W->cols, H->rows
 9 int dr[4] = {0, 1, -1, 0};
10 int dc[4] = {-1, 0, 0, 1};
11 
12 bool inmap(int r, int c)
13 {
14     if(r>=1 && r<=H && c>=1 && c<=W)
15         return true;
16     else
17         return false;
18 }
19 
20 void dfs(int now_r, int now_c)
21 {
22     for(int i=0; i<4; i++)
23     {
24         int r = now_r + dr[i];
25         int c = now_c + dc[i];
26         if(inmap(r,c) && map[r][c] && !visit[r][c])
27         {
28             answer++;
29             visit[r][c] = true;
30             dfs(r, c);
31         }
32         
33     }
34 }
35 
36 int main() 
37 {
38     int i, j, start_r, start_c;
39     while( cin >> W >> H)
40     {
41         if(W == 0 && H == 0)  
42             break;
43         memset(visit, false, sizeof(visit));
44         
45         for(i=1; i<=H; i++)
46             for(j=1; j<=W; j++)
47             {
48                 char c;
49                 cin >> c;
50                 if(c == ‘.‘)
51                     map[i][j] = true;
52                 else
53                 {
54                     if(c == ‘#‘)
55                         map[i][j] = false;
56                     else
57                     {
58                         map[i][j] = true;
59                         visit[i][j] = true;
60                         start_r = i;
61                         start_c = j;
62                     }
63                 }
64             }
65         answer = 1;
66         dfs(start_r, start_c);
67         cout << answer << endl;
68     }
69     
70     return 0;
71 }