图的广度优先搜索

#include<stdio.h>
#include<string.h>
int count;
char room[20][20];
int reached[20][20];
int m,n;
void move(int x,int y){
    //printf("x%d,y%d,room[%d][%d]%c\n",x,y,x,y,room[x][y]);
    if(x>=0&&x<m&&y>=0&&y<n&&(room[x][y]=='.'||room[x][y]=='@'))
        if(reached[x][y]==0){
            reached[x][y]=1;
            count++;
            move(x-1,y);
            move(x+1,y);
            move(x,y-1);
            move(x,y+1);
        }
}
int main(){
    int i,j; 
    while(scanf("%d%d",&m,&n)!=EOF){
        i=j=-1;
        count=0;
        for(int k=0;k<m;k++){
            scanf("%s",room[k]);
            //printf("test:%s\n",room[k]);
            memset(reached[k],0,sizeof(int)*n);
            if(i==-1){
                if(strchr(room[k],'@')!=NULL){
                    i=k;
                    j=(int)(strchr(room[k],'@')-room[k]);
                } 
            }
        }
        move(i,j);
        printf("%d\n",count);
    }
}

https://www.nowcoder.com/practice/5017fd2fc5c84f78bbaed4777996213a?tpId=3&&tqId=10879&rp=1&ru=/activity/oj&qru=/ta/hackathon/question-ranking