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CDZSC_2015寒假新人(4)——搜索 B

Description

There is a rectangular room, covered with square tiles. Each tile is colored either red or black. A man is standing on a black tile. From a tile, he can move to one of four adjacent tiles. But he can‘t move on red tiles, he can move only on black tiles. 

Write a program to count the number of black tiles which he can reach by repeating the moves described above. 
 

Input

The input consists of multiple data sets. A data set starts with a line containing two positive integers W and H; W and H are the numbers of tiles in the x- and y- directions, respectively. W and H are not more than 20. 

There are H more lines in the data set, each of which includes W characters. Each character represents the color of a tile as follows. 

‘.‘ - a black tile 
‘#‘ - a red tile 
‘@‘ - a man on a black tile(appears exactly once in a data set) 
 

Output

For each data set, your program should output a line which contains the number of tiles he can reach from the initial tile (including itself). 
 

Sample Input

6 9
....#.
.....#
......
......
......
......
......
#@...#
.#..#.
11 9
.#.........
.#.#######.
.#.#.....#.
.#.#.###.#.
.#.#..@#.#.
.#.#####.#.
.#.......#.
.#########.
...........
11 6
..#..#..#..
..#..#..#..
..#..#..###
..#..#..#@.
..#..#..#..
..#..#..#..
7 7
..#.#..
..#.#..
###.###
...@...
###.###
..#.#..
..#.#..
0 0
 

Sample Output

45
59
6
13
 
 
 
思路:就是从@开始上下左右4个方向把.全部找到,dfs就好
 
 
 
 1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 using namespace std; 5 char str[25][25]; 6 int vis[25][25],w,h,sum; 7 int x[]={-1,1,0,0}; 8 int y[]={0,0,-1,1}; 9 void dfs(int i,int j)10 {11     for(int k=0; k<4; k++)12     {13         if(i+x[k]<h&&i+x[k]>=0&&j+y[k]<w&&j+y[k]>=0&&vis[i+x[k]][j+y[k]]==0&&str[i+x[k]][j+y[k]]!=#)14         {15             sum++;16             vis[i+x[k]][j+y[k]]=1;17             dfs(i+x[k],j+y[k]);18         }19     }20 }21 int main()22 {23 #ifdef CDZSC_OFFLINE24     freopen("in.txt","r",stdin);25 #endif26     int i,j;27     while(scanf("%d%d",&w,&h)&&w!=0&&h!=0)28     {29         memset(vis,0,sizeof(vis));30         sum=1;31         for(i=0; i<h; i++)32         {33             scanf("%s",str[i]);34         }35         for(i=0; i<h; i++)36         {37             for(j=0; j<w; j++)38             {39                 if(str[i][j]==@)40                 {41                     vis[i][j]=1;42                     dfs(i,j);43                 }44             }45         }46         printf("%d\n",sum);47     }48     return 0;49 }

 

CDZSC_2015寒假新人(4)——搜索 B