dfs入门（2）

dfs入门经典（2）

Xenial Xerus

 

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) 
The end of the input is indicated by a line consisting of two zeros. 

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

/*

dfs搜索即可

*/

#include<stdio.h>using namespace std;int N,M,ans;char Map[100+5][100+5];int vis[4][2]={{-1,0},{0,1},{1,0},{0,-1}};void dfs(int x,int y){    for(int i=0;i<4;i++)    {        int x_next=x+vis[i][0];        int y_next=y+vis[i][1];        if(x_next>=0&&x_next<N  &&  y_next>=0&&y_next<M  && Map[x_next][y_next]=='.')        {            Map[x_next][y_next]='*';            ans++;            dfs(x_next,y_next);        }    }}int main(){    while(scanf("%d%d",&M,&N))    {        ans=1;        if(M==0||N==0)  break;        else        {            for(int i=0;i<N;i++)                scanf("%s",Map[i]);            for(int i=0;i<N;i++)                for(int j=0;j<M;j++)            {                if(Map[i][j]=='@')                {                    Map[i][j]='*';                    dfs(i,j);                }            }            printf("%d\n",ans);        }    }    return 0;}