HDU 1312 Red and black dfs

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#include <iostream>
#include <algorithm>
#include <string.h>
using namespace std;
const int N=30;
int w,h,step;
char array[N][N];
int ma[N][N];
//int dir[4][2]={{0,1},{1,0},{-1,0},{0,-1}};
int dir[4][2]= {0,1,0,-1,1,0,-1,0};

void dfs(int x,int y){
	if(x<0||y<0||x>=h||y>=w)
		return;
		
	int i,j,k;	
	ma[x][y]=1;
	++step;
	
	for(k=0;k<4;k++){
		i=x+dir[k][0];
		j=y+dir[k][1];
		if(ma[i][j]==1||array[i][j]=='#')
			continue;

		dfs(i,j);
	}
}

int main(){
	int i,j,sx,sy;
	while(scanf("%d %d",&w,&h)){
		if(w==0&&h==0)
			break;
		memset(ma,0,sizeof(ma));			
		for(i=0;i<h;i++){
			scanf("%s",array[i]);
		}
		
		for(i=0;i<h;i++){
			for(j=0;j<w;j++){
				if(array[i][j]=='@'){
					sx=i;
					sy=j;
					break;
				}
			}
		}
		
		step=0;

		dfs(sx,sy);
		printf("%d\n",step);
	}
	return 0;
}