HDU 1312 Red and Black

Problem 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

4559613
搜索基础
#include<iostream>#include<cstdio>#include<string>using namespace std;char map[25][25];int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};int w,h,s;void dfs(int x,int y){int i,j,nx,ny;for(i=0;i<4;i++){nx=x+dx[i],ny=y+dy[i];if(nx>0&&nx<=h&&ny>0&&ny<=w&&map[nx][ny]=='.'){map[nx][ny]='#';s++;dfs(nx,ny);}}}int main(){int i,j;while(scanf("%d%d",&w,&h),w||h){for(i=1;i<=h;i++)for(j=1;j<=w;j++)cin>>map[i][j];s=1;for(i=1;i<=h;i++)for(j=1;j<=w;j++){if(map[i][j]=='@'){map[i][j]='#';dfs(i,j);}}printf("%d\n",s);}return 0;}