hdu1312(DFS 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
#include<stdio.h>#include<iostream>using namespace std;int n,m,dir[4][2]={{1,0},{-1,0},{0,1},{0,-1}},sum;char map[25][25];int DFS(int i,int j){    int e;    map[i][j]='#';    sum++;    for(e=0;e<4;e++)    if(i+dir[e][0]>=0&&i+dir[e][0]<n&&j+dir[e][1]>=0&&j+dir[e][1]<m)    if(map[i+dir[e][0]][j+dir[e][1]]!='#')    DFS(i+dir[e][0],j+dir[e][1]);}int main(){    int i,j,pi,pj;    while(scanf("%d%d",&m,&n)>0&&(m||n))    {        for(i=0;i<n;i++)        {            getchar();            for(j=0;j<m;j++)            {                scanf("%c",&map[i][j]);                if(map[i][j]=='@')                {                    pi=i;pj=j;                }            }        }        sum=0;        DFS(pi,pj);        printf("%d\n",sum);    }}