BNUOJ 1038 Flowers(BFS)

#include<stdio.h>
#include<queue>
#include<string.h>
using namespace std;
const int N = 105 ;
struct node
{
    int x,y;
};
char mapt[N][N];
int vist[N][N],n,m;
int dir[4][2]={0,1,0,-1,1,0,-1,0};

int bfs(int x,int y)
{
    queue<node>q;
    node now,pre;
    int ans=1,flag=1;
    vist[x][y]=1;
    now.x=x; now.y=y;
    q.push(now);
    while(!q.empty())
    {
        pre=q.front(); q.pop();
        for(int e=0; e<4; e++)
        {
            now.x=pre.x+dir[e][0];
            now.y=pre.y+dir[e][1];
            if(now.x<0||now.x>=n||now.y<0||now.y>=m)
            {
                flag=0; continue;
            }
            if(!vist[now.x][now.y]&&mapt[now.x][now.y]=='.')
            {
                vist[now.x][now.y]=1;
                ans++;
                q.push(now);
            }
        }
    }
    if(flag==0) ans=0;
    return ans;
}
int main()
{
    //int n,m;
    while(scanf("%d%d",&n,&m)>0)
    {
        for(int i=0; i<n; i++)
            scanf("%s",mapt[i]);
        int ans=0;
        memset(vist,0,sizeof(vist));
        for(int i=0; i<n; i++)
            for(int j=0; j<m; j++)
            if(!vist[i][j]&&mapt[i][j]=='.')
             ans+=bfs(i,j);
        printf("%d\n",ans);
    }
}