使用队列保存未被检测的节点 节点按照深度优先的次序被访问 并依次压入队列中 并以相反的次序进行出队列

#include<iostream>
#include<stack>
#include<queue>

using namespace std;

int dir[4][2]={1,0,-1,0,0,1,0,-1};

struct point{
    int x,y,step;
};

int bfs(point s,point e,int map[9][9]){
    queue<point> tp;
    point t;//临时变量
    //s->之前
    //e->目标
    s.step = 0; //计数
    map[s.x][s.y] = 1;  //走过就标记为1
    tp.push(s);  //初始化队列
    while(!tp.empty()){
        s=tp.front();//队首
        tp.pop();//delete
        if(s.x==e.x&&s.y==e.y)
            return s.step;
        for(int i = 0;i<4;i++){
            t.x=s.x+dir[i][0];
            t.y=s.y+dir[i][1];
            if(map[t.x][t.y]==0){//可以走
                t.step=s.step+1;
                map[t.x][t.y]=1;//标记为墙
                tp.push(t);
            }
        }
    }
}
int main(){
    int t;
    scanf("%d",&t);
    while(t--){
        point s,e;
        int map[9][9]= {1,1,1,1,1,1,1,1,1,
                        1,0,0,1,0,0,1,0,1,
                        1,0,0,1,1,0,0,0,1,
                        1,0,1,0,1,1,0,1,1,
                        1,0,0,0,0,1,0,0,1,
                        1,1,0,1,0,1,0,0,1,
                        1,1,0,1,0,1,0,0,1,
                        1,1,0,1,0,0,0,0,1,
                        1,1,1,1,1,1,1,1,1,};
        scanf("%d%d%d%d",&s.x,&s.y,&e.x,&e.y);
        printf("%d\n",bfs(s,e,map));
    }
    return 0;
}